Abstract: Disclosed herein is a pest and odor preventive sanitary drain which utilizes the continuous property of liquids and permits a twisting downward discharge of waste water and keeps a certain waste water retention level in the water holder therebeneath so that the inlet of the discharge pipe is obstructed; in addition, a deodorizer is used for complete prevention of odor and pests towards a house so that indoor sanitation is maintained and human health is protected.