A seat lock device includes: a hook member; and a cam plate. The hook member includes: a hook inclined edge surface and is rotationally biased by contact with a striker entering; an engaging groove into which the striker entering fits after crossing the hook inclined edge surface to bring the hook member into a locked position; a restraining pin; and an interlock pin, the cam plate is set to a limiting position when the hook member engages with the striker and is switched to an allowing position when the striker enters and when an operation performed to release an engagement of the striker, and the cam plate includes: a cam surface that contacts with the restraining pin to rotationally bias the hook member; and an interlock surface with which the interlock pin contacts when the hook member has turned from the locked position.