PURPOSE: To effectively adjust a reversal position of a reversing spring by adjusting a position of the reversing spring with its tilt relatively small, that is, by inserting a reversal position adjusting device to a fixed part of a fixing member for fixing the reversing spring.

CONSTITUTION: A reversal position adjusting screw 30 is screwed to a screw hole 31 of a fixed part 27 till a fixing member 5 is deformed with a shaft protrusion 23 serving as an axis. Here in the case of using a reset button 8 as a manual reset button, since a reversal position D of a reversing spring 4 is positioned in an operating part moving range (a) at top time, the reversing spring 4 is reversed. However, since the reversal position D of the reversing spring 14, reversed at top time, is positioned in a right side of the operating member moving range (a) from an operating member stop position C in the case of using the reset button 8 as an automatic resetting stopper, the reversing spring 4 can not be automatically reset. Next, when a screwing amount of the screw 30 is decreased, in the case of using the reset button 8 as an automatic resetting stopper, since the reversal position D is placed in a left side of the stop position C, the spring 4 can be automatically reset before reversing.