A knocking sensor which includes: a piezoelectric element; a support member having a support body portion, the support body portion including a support surface directly or indirectly supporting the piezoelectric element; and a resin coating covering the piezoelectric element and at least a part of the support member, the resin coating having an outside portion covering an outer circumference of the piezoelectric element and an outer circumference of the support body portion. The support body portion of the support member has a first engagement portion on the base end side thereof. The resin coating has a curved portion which extends from the outside portion toward the interfacial direction inner side, and curves toward the base end side of the support body portion. Further, the curved portion includes a second engagement portion which engages the first engagement portion.