A seat lock device comprising: a hook member elastically rotationally biased in a positive direction; and a cam plate elastically rotationally biased in the positive direction, wherein the hook member includes: a hook inclined edge surface that is provided on another end relative to a support shaft near one end and is rotationally biased in a negative direction by contact with a striker entering; an engaging groove with a depth 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 protruding sideways; and an interlock pin protruding sideways, the cam plate is set to a limiting position that limits turning of the hook member in the negative direction when the hook member engages with the striker to be at the locked position and is switched to an allowing position that allows the turning of the hook member in the negative direction when the striker enters and when an operation to release an engagement of the striker has been performed, and the cam plate includes: a cam surface that comes into contact with the restraining pin to rotationally bias the hook member in the positive direction when being at the limiting position; and an interlock surface with which the interlock pin comes into contact before the striker escapes from the engaging groove when the hook member has turned in the negative direction from the locked position. a hook member elastically rotationally biased in a positive direction; and a cam plate elastically rotationally biased in the positive direction, wherein the hook member includes: a hook inclined edge surface that is provided on another end relative to a support shaft near one end and is rotationally biased in a negative direction by contact with a striker entering; an engaging groove with a depth 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 protruding sideways; and an interlock pin protruding sideways, a hook inclined edge surface that is provided on another end relative to a support shaft near one end and is rotationally biased in a negative direction by contact with a striker entering; an engaging groove with a depth 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 protruding sideways; and an interlock pin protruding sideways, the cam plate is set to a limiting position that limits turning of the hook member in the negative direction when the hook member engages with the striker to be at the locked position and is switched to an allowing position that allows the turning of the hook member in the negative direction when the striker enters and when an operation to release an engagement of the striker has been performed, and the cam plate includes: a cam surface that comes into contact with the restraining pin to rotationally bias the hook member in the positive direction when being at the limiting position; and an interlock surface with which the interlock pin comes into contact before the striker escapes from the engaging groove when the hook member has turned in the negative direction from the locked position. a cam surface that comes into contact with the restraining pin to rotationally bias the hook member in the positive direction when being at the limiting position; and an interlock surface with which the interlock pin comes into contact before the striker escapes from the engaging groove when the hook member has turned in the negative direction from the locked position.