Provided is a heat treatment method for a cam piece, and the cam piece has an insertion hole into which a cam shaft is inserted, a base portion configuring a base circle of a cam, and a nose portion configuring a cam ridge. The heat treatment method for the cam piece includes: a first step of using a jig formed into a shape having a cavity, the jig being inserted into the insertion hole such that the cavity is located between an inner circumferential surface of the nose portion of the cam piece and a central axis of the jig; and a second step of heating the cam piece from an outer circumferential surface side by high-frequency induction heating in a state in which the jig is inserted in the insertion hole of the cam piece.