PROBLEM TO BE SOLVED: To provide a pharmaceutical composition which little produces side effects, has a reinforced action for expressing an excellent penis erection function in a small usage, and is used for improving the failure of the penis erection function.SOLUTION: This pharmaceutical composition contains a PDE5 inhibitor selected from the group consisting of sildenafil, vardenafil, tadalafil, udenafil and their pharmacologically acceptable salts, and Agkistrodon blomhoffii obtained by taking out internal organs from Agkistrodon halys, peeling the skin, long extending the left body, and drying the extended body, as active ingredients.
