To provide a resonator capable of vibrationally welding an upper side inside frame part and a lower side inside frame part, without reducing the volume of the resonator.

Since curved parts 22c and 33c for enhancing rigidity of connection parts 22b and 33b are formed in at least a part of a pair of connecting parts 22b and 33b of the upper side inside frame part 22 and the lower side inside frame part 33, the rigidity of the connection parts 22b and 33b can be enhanced more than when the curved parts 22c and 33c are not arranged in the connection parts 22b and 33b. As a result of it, even if a tool is not arranged just under a welding part of the upper side inside frame part 22 and the lower side inside frame part 33, the connection parts 22b and 33b can be restrained from being deformed (deflected) in vibrating. Thus, the upper side inside frame part 22 and the lower side inside frame part 33 can be vibrationally welded without reducing the volume of the resonator 10.