A three-dimensional cam mechanism capable of selecting a cam guide surface shape freely to improve the degree of freedom for selecting a target locus on the follower side, transmitting power between orthogonal axes and performing a reversible operation. A three-dimensional cam guide surface (2 (3)) is formed in a cam (1), and the cam guide surface (2) is caused to guide a cam follower (6 (7)) formed at a predetermined angle at one end of a follower side link (4), so that the rotational movement of the cam (1) is translated into the swinging movement at the other end of the follower side link (4). Thus, smooth operations of the cam are obtained by the selection of the shape of a supporting member and by the free design of the cam guide surface shape, without being limited to the power transmission between the orthogonal axes or followed by backlash.