The present relates to a suction foundation in which is penetrated into the seabed by a vacuum pressure of a suction pump, thereby providing a desired foundation support force. The suction foundation includes a hollow caisson having an opening at a lower end thereof, where the suction pump is connected to the hollow caisson and the suction pump allows the hollow caisson to penetrate into the seabed while discharging a fluid in the hollow caisson to an outside thereof by using the vacuum pressure of the suction pump, a lower skirt provided along a circumference of the opening of the hollow caisson and formed into a wave shape having a series of teeth, and having wedge-shaped cross-sections, and a stiffener increasing rigidity of the lower skirt by increasing thickness of a predetermined portion of the lower skirt.