PURPOSE: To provide a parasiticide having an effect against all parasites living in human digestive tracts, by comprising a food selected from beefsteak plant, Japanese horseradish, ginger and garlic.

CONSTITUTION: A parasiticide contains as an active ingredient a food selected from beefsteak plant, Japanese horseradish, ginger and garlic, an extract thereof with water, an aqueous alcohol, etc., or perillyl aldehyde and/or perillyl alcohol which is an ingredient contained in the beefsteak plant. The dose of the parasiticide is 100W500mg/day orally and 0.5W100mg/day parenterally as the weight of the perillyl aldehyde or perillyl alcohol.