To prevent a spark discharge certainly in the contact of a butt switch with a simple structure.

The butt switch (4) is divided into two contactor boards (4a), (4b), and a power contactor convex part (5), a signal contactor convex part (6), and a power contactor concave part (7), a signal concave part (8) are releasably arranged on a contactor board (4a) and (4b) separately, and the protruding length of the power contactor convex part (5) is determined to be longer than the protruding length of the signal contactor convex part (6). Therefore, after the power contactor convex part is fitted into the power contactor concave part, the signal contactor convex part is fitted into the signal concave part to start sending power to the power contactor, and before the power contactor convex part is separated from the power contactor concave part, the signal contactor convex part is separated from the signal concave part to stop sending power to the power contactor, which can prevent the spark discharge between the power contactors.