A phase lag cell and an antenna including the same are disclosed. A phase lag cell according to one embodiment of the present invention comprises: a plane reflector; a substrate spaced apart and positioned at a predetermined distance from the reflector; and a phase lag circuit formed at one side of the substrate such that L-shaped patterns are formed to be vertically and horizontally symmetrical around a cross-shaped slot, and a stub having a predetermined length is extended from the end of each L-shaped pattern.