To provide a heat sterilization agent and a heat sterilization method of food which exhibit heat sterilization effect against Bacillus even by low-temperature sterilization at 80-100°C and at normal pressure without affecting the color tone and flavor of food having a pH of 5 or higher.

A food item having a pH of 5 or higher contains 0.05-0.2 mass% L-ascorbic acid and 0.1-0.3 mass% trisodium citrate and is subjected to heat sterilization at 80-100°C.