To prevent a protective cover from moving in an unintended direction of a worker in a portable cutter having a movable protective cover.

The portable cutter (1) has a motor, a cutting means (5) driven by the motor, a housing (7) for storing the motor, and the movable protective cover (11) mounted on the housing and covering the exposed part of the cutting means during non-cutting work. The portable cutter further has an acceleration sensor (31) for detecting the attitude change of the portable cutter and a lock mechanism 16 for restricting the movement of the protective cover (11) when the abrupt attitude change of the portable cutter is detected by the acceleration sensor (31) during cutting work. After the abrupt attitude change of the portable cutter (1) is detected by the acceleration sensor 31, secondary movement of the protective cover (11) automatically restored to a normal state (closed state) is restricted.