To provide a clamping device, reducing man-hours related to clamping work.

This clamping device 1 includes: an arm 4 formed by one end 41 abutting on a product 2 placed on a bed 3, the other end 42 abutting on the bed 3 and an intermediate part 43 located between one end 41 and the other end 42; a bolt 5 locked at the head 51 on the bed 3 and penetrating the intermediate part 43 of the arm 4 by a screw part 52; and a nut 6 engaged with the screw part 52 of the bolt 5 penetrating the intermediate part 43, wherein the nut 6 is screwed with the screw part 52 of the bolt 5 to hold the product 2 between one end 41 of the arm 4 and the bed 3. The clamping device further includes a block 7 previously rotatably connected to the other end 42 of the arm 4 and abutting on the bed 3, wherein the other end 42 of the arm 4 directly abuts on the bed 3 or abuts on the bed 3 through the block 7.