As I asked in here, I learned that the environment variable of PATH is different depending on how I launch the app.
Using 'aquamacs' from command line is run on top of bash, so the PATH variable is copied to the PATH variable in eshell.
But, how about the clicking the Aquamacs icon method? What PATH variable is set, when I click an app with Mac OS X? And how the PATH variable is set in that way?