We conducted fecal analysis of the larvae of the Japanese giant salamander Andrias japonicus and environmental analysis to reveal its food habits. In fecal analysis, Ephemeroptera and Plecoptera larvae were observed as the most dominant preys. Choroterpes sp. was the dominant species in Ephemeroptera. The dominant prey species emerge from March to May and it causes a decrease in prey species; i.e., larvae are considered to flow down to search for prey species in a wider area. Food habits are also suggested to change with increase in larvae body size.