To provide a foundation constructing method according to which leveling of a rise portion upper surface of a foundation such as a continuous footing or a mat foundation, and densification of the foundation are simultaneously implemented, construction procedures are simplified, and construction costs and the number of days necessary for the construction are drastically reduced, and to provide a pressurizing device for use in the constructing method, and the continuous footing or the mat foundation constructed by the method.

According to the foundation constructing method, level concrete is placed on the ground surface, and base concrete is placed on an upper surface of the level concrete, followed by forming a rise portion on the base concrete. Then the concrete is pressurized until the rise portion upper surface becomes equal to a desired level, to extract water and air present in the concrete in the rise portion, and when the upper surface reaches the predetermined level, pressurizing work is terminated.