To provide a lead frame chucking device which does not require much labor to make chucking.

A chucking device is equipped with a holding tool 2 to be positioned over a lead frame 1 with possibility of moving in the vertical direction and a supporting tool 3 to be positioned below the lead frame 1. The lead frame 1 is pinched by the holding tool 2 which has sunk and the supporting tool 3. The risk of breakage of lead frame 1 can be lessened by chucking it in the thickness direction unlikely to fold, compared with the case in which lead frame 1 is chucked in the shorter direction. The thickness of the lead frame 1 is approx. constant, and there is no need to make fine adjustment such as restricting the spacing between the holding tool 2 and supporting tool 3 in accordance with the type of lead frame 1 which may differ in the shorter direction dimension.