PROBLEM TO BE SOLVED: To provide a composition having an improving effect on the number of sperms, being suitable for industrial production due to easier acquisition of ingredients than a conventional technology.SOLUTION: The above mentioned purpose of the present application is achieved by a sperm improving agent and semen improving agent comprising Peucedanum japonicum or extract thereof, a medicament for preventing and treating male sterility comprising Peucedanum japonicum or extract thereof as an active ingredient, and a composition for oral administration comprising 1.5 to 10 g of dried leaf of Peucedanum japonicum or extract thereof as a daily dosage.