--- a/toolkit/components/telemetry/Scalars.yaml
+++ b/toolkit/components/telemetry/Scalars.yaml
@@ -1746,16 +1746,33 @@ widget:
     expires: never
     kind: boolean
     notification_emails:
       - mnakano@mozilla.com
     release_channel_collection: opt-out
     record_in_processes:
       - 'main'
 
+  ime_name_on_mac:
+    bug_numbers:
+      - 1215818
+    description: >
+      Name of IME which was selected by users on macOS.  The value is Input
+      Source ID if non-Japanese IME was open.  Otherwise, if Japanese IME was
+      open, the value is Bundle ID.  Input Source ID includes input mode, but
+      Bundle ID does not include input mode.
+    keyed: true
+    expires: never
+    kind: boolean
+    notification_emails:
+      - mnakano@mozilla.com
+    release_channel_collection: opt-out
+    record_in_processes:
+      - 'main'
+
 # The following section contains memory reporter counters.
 memoryreporter:
   max_ghost_windows:
     bug_numbers:
       - 1454724
     description: >
       The maximum number of leaked ghost windows seen.
     expires: "66"

--- a/widget/cocoa/TextInputHandler.h
+++ b/widget/cocoa/TextInputHandler.h
@@ -219,16 +219,17 @@ public:
 
   bool GetInputSourceType(nsAString &aType)
   {
     NS_ENSURE_TRUE(mInputSource, false);
     return GetStringProperty(kTISPropertyInputSourceType, aType);
   }
 
   bool IsForRTLLanguage();
+  bool IsForJapaneseLanguage();
   bool IsInitializedByCurrentInputSource();
 
   enum {
     // 40 is an actual result of the ::LMGetKbdType() when we connect an
     // unknown keyboard and set the keyboard type to ANSI manually on the
     // set up dialog.
     eKbdType_ANSI = 40
   };

--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -7,16 +7,17 @@
 #include "TextInputHandler.h"
 
 #include "mozilla/Logging.h"
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/AutoRestore.h"
 #include "mozilla/MiscEvents.h"
 #include "mozilla/MouseEvents.h"
+#include "mozilla/Telemetry.h"
 #include "mozilla/TextEventDispatcher.h"
 #include "mozilla/TextEvents.h"
 
 #include "nsChildView.h"
 #include "nsObjCExceptions.h"
 #include "nsBidiUtils.h"
 #include "nsToolkit.h"
 #include "nsCocoaUtils.h"
@@ -828,16 +829,24 @@ TISInputSourceWrapper::IsForRTLLanguage(
     NS_ENSURE_TRUE(ret, ret);
     char16_t ch = str.IsEmpty() ? char16_t(0) : str.CharAt(0);
     mIsRTL = UTF16_CODE_UNIT_IS_BIDI(ch);
   }
   return mIsRTL != 0;
 }
 
 bool
+TISInputSourceWrapper::IsForJapaneseLanguage()
+{
+  nsAutoString lang;
+  GetPrimaryLanguage(lang);
+  return lang.EqualsLiteral("ja");
+}
+
+bool
 TISInputSourceWrapper::IsInitializedByCurrentInputSource()
 {
   return mInputSource == ::TISCopyCurrentKeyboardInputSource();
 }
 
 void
 TISInputSourceWrapper::Select()
 {
@@ -3045,16 +3054,45 @@ IMEInputHandler::OnCurrentTextInputSourc
                                                 const void* aObject,
                                                 CFDictionaryRef aUserInfo)
 {
   // Cache the latest IME opened mode to sLatestIMEOpenedModeInputSourceID.
   TISInputSourceWrapper tis;
   tis.InitByCurrentInputSource();
   if (tis.IsOpenedIMEMode()) {
     tis.GetInputSourceID(sLatestIMEOpenedModeInputSourceID);
+    // Collect Input Source ID which includes input mode in most cases.
+    // However, if it's Japanese IME, collecting input mode (e.g.,
+    // "HiraganaKotei") does not make sense because in most languages,
+    // input mode changes "how to input", but Japanese IME changes
+    // "which type of characters to input".  I.e., only Japanese IME
+    // users may use multiple input modes.  If we'd collect each type of
+    // input mode of Japanese IMEs, it'd be difficult to count actual
+    // users of each IME from the result.  So, only when active IME is
+    // a Japanese IME, we should use Bundle ID which does not contain
+    // input mode instead.
+    nsAutoString key;
+    if (tis.IsForJapaneseLanguage()) {
+      tis.GetBundleID(key);
+    } else {
+      tis.GetInputSourceID(key);
+    }
+    // 72 is kMaximumKeyStringLength in TelemetryScalar.cpp
+    if (key.Length() > 72) {
+      if (NS_IS_LOW_SURROGATE(key[72 - 1]) &&
+          NS_IS_HIGH_SURROGATE(key[72 - 2])) {
+        key.Truncate(72 - 2);
+      } else {
+        key.Truncate(72 - 1);
+      }
+      // U+2026 is "..."
+      key.Append(char16_t(0x2026));
+    }
+    Telemetry::ScalarSet(Telemetry::ScalarID::WIDGET_IME_NAME_ON_MAC,
+                         key, true);
   }
 
   if (MOZ_LOG_TEST(gLog, LogLevel::Info)) {
     static CFStringRef sLastTIS = nullptr;
     CFStringRef newTIS;
     tis.GetInputSourceID(newTIS);
     if (!sLastTIS ||
         ::CFStringCompare(sLastTIS, newTIS, 0) != kCFCompareEqualTo) {
@@ -3140,25 +3178,28 @@ IMEInputHandler::DebugPrintAllIMEModes()
     CFArrayRef list = CreateAllIMEModeList();
     MOZ_LOG(gLog, LogLevel::Info, ("IME mode configuration:"));
     CFIndex idx = ::CFArrayGetCount(list);
     TISInputSourceWrapper tis;
     for (CFIndex i = 0; i < idx; ++i) {
       TISInputSourceRef inputSource = static_cast<TISInputSourceRef>(
         const_cast<void *>(::CFArrayGetValueAtIndex(list, i)));
       tis.InitByTISInputSourceRef(inputSource);
-      nsAutoString name, isid;
+      nsAutoString name, isid, bundleID;
       tis.GetLocalizedName(name);
       tis.GetInputSourceID(isid);
+      tis.GetBundleID(bundleID);
       MOZ_LOG(gLog, LogLevel::Info,
-        ("  %s\t<%s>%s%s\n",
+        ("  %s\t<%s>%s%s\n"
+         "    bundled in <%s>\n",
          NS_ConvertUTF16toUTF8(name).get(),
          NS_ConvertUTF16toUTF8(isid).get(),
          tis.IsASCIICapable() ? "" : "\t(Isn't ASCII capable)",
-         tis.IsEnabled() ? "" : "\t(Isn't Enabled)"));
+         tis.IsEnabled() ? "" : "\t(Isn't Enabled)",
+         NS_ConvertUTF16toUTF8(bundleID).get()));
     }
     ::CFRelease(list);
   }
 }
 
 //static
 TSMDocumentID
 IMEInputHandler::GetCurrentTSMDocumentID()