An inertial sensor includes: a substrate; a fixing part arranged at one surface of the substrate; a moving element having an opening and configured to swing about a rotation axis along a first direction; a support beam supporting the moving element as the rotation axis in the opening of the moving element; and a support part supporting the support beam. The support part includes a first part fixed to the fixing part, and a second part formed only of a part not fixed to the fixing part. A length in the first direction of the second part is longer than a length in the first direction of the first part.