A snap hook comprises a base member having a J-shaped hook and a flexible member, and a slider mounted on the base member for movement in directions perpendicular to the longitudinal direction of the base member to open and close the J-shaped hook, wherein the hook is normally held closed by the slider biased by the flexible member, and when the slider is depressed with a ring or the like, the slider is moved inwardly to open the hook so that the ring or the like can be hooked.