To provide a clamp mechanism of a feed device of a transfer press capable of adequately holding a workpiece of different contour by reliably operating a pair of holding arms at the same timing.

The clamp mechanism comprises first moving bodies 2A, 2B provided on a base 1 in a longitudinally movable manner, second moving bodies 4 provided on the first moving bodies 2A, 2B in a longitudinally movable manner, a pair of holding arms 5A, 5B in which intermediate parts thereof are pivotally supported by the second moving bodies 4 and protruded forwardly, and holding pieces 55 facing each other are turnably movable outwardly and inwardly, a pair of operation arms 6A, 6B in which intermediate parts thereof are pivotally supported by the first moving bodies 2A, 2B and protruded forwardly, and fore-end rollers 62 thereof are abutted on a back side in the facing direction of arm part base ends 52 of the holding arms 5A, 5B, a coil spring 82 for energizing an operation body 81 forwardly, and link arms 7A, 7B with both ends thereof turnably connected to the operation body 81 and the base ends of the operation arms 6A, 6B.