Provided is a simple and easy method of producing an innoxious dry earthworm powder, while suppressing inactivation of the enzymes contained in earthworms. In the method, a homogenate obtained by grinding living earthworms is freeze-dried and the dried product is heat-treated at a temperature of 110°C or higher but lower than 130°C. Preferably, the method according to the present invention comprises further a process for preparation of the living earthworms, which precedes the grinding step, comprising the steps of: standing the living earthworms under light for 10 to 50 hours； removing the dirt formed on the skin thereof, bringing the earthworms into contact with an organic acid for 30 seconds or less； diluting the acid with addition of water to adjust the pH of the aqueous acidic solution to a pH in the range of 2 to 5； standing the earthworm mixture under the pH condition for 3 to 180 minutes； and then washing the earthworms with water.
