To provide a reinforcing part in an upper panel itself fixing an upper blade, prevent weight thereof from increasing, surely suppress an escape in the direction orthogonal to the cutting direction in an intermediate part of the upper panel, so that a long-scaled metal thin plate can be well cut, in a metal plate cutter cutting the metal plate by the lowering down upper blade and a fixed lower blade.

This device is constituted such that relating to a lower panel 3 integrally fixing a lower blade 2 along the lengthwise direction to be fixedly provided in a horizontal condition by a supporting frame 1, a vertical plate-shaped upper panel 6 integrally fixing an upper blade 5 opposed to the lower blade 2 in a lower end part is vertically moved through a turn shaft 9 turned by drive force 16 and link mechanisms 11a, 12a, 11b, 12b converting turning of the turn shaft 9 into vertical movement. Here, so as to be along a vertical plate surface of the upper panel 6, a support fixed member 4 is fixedly provided in a horizontal condition by the supporting frame 1, also over the support fixed member 4 and the upper panel 6, a lengthwise direction suitable part thereof, a guide holding mechanism 7 is provided, which is for holding the upper panel 6 capable of vertically moving and in parallel relating to the support fixed member 4.