A hand device for working robot which can be downsized is provided. The device consists of a robot hand 10, a link means 40 and a workpiece drop prevention means. The robot hand 10 includes a hand base 20, a pair of fingers 21, 21 protruding from the hand base 20 and a movable core 25 provided with a cylinder 24. The link means 40 includes a lever and a connecting pad 43 for connecting the lever and the movable core 25. A workpiece drop prevention means 60 includes a protrusion stick 50 which is supported by a supporting rail 51, a coil spring and an air cylinder for recess 53.