To provide a portable metal plate cutting device capable of cutting even a vertically arranged metal plate, being easily carried up to an installation place of the metal plate and independently operating.

This portable metal plate cutting device 110 for cutting the metal plate D such as a shutter is provided with a housing 10 having an internal space 65 opened in one direction, a rotary cutter 70 rotatably supported in the housing 10 so that a part of a plurality of outer peripheral cutting blades 77 formed on an outer periphery may be projected from an opening of the housing 10, and a slit 83 mounted at an opening edge 65a of the housing 10 to pass the projected outer peripheral cutting blades 77. The cutting device 110 includes a pressing member 80 mounted to be approachable/separable to/from the opening edge 65a of the housing 10 to be pressed to the vicinity of a cutting portion when cutting the metal plate D by the rotary cutter 70.