PURPOSE: To beforehand avoid the dangerous situation that a machine body runs out at unintentional speed when altering the direction of a handle, by mounting a mechanism that holds a speed change gear at the machine body side under a speed change neutral condition when changing an attitude of the handle.

CONSTITUTION: In a device that can alter an attitude of an operation handle 1 before and behind to a machine body 2 by rotation around upper and lower axial cores X, a mechanism 4 is mounted which holds a speed change gear 3 under a speed change neutral condition when changing the attitude of the handle 1. This mechanism 4 is formed by a moving portion material 15, which is downward shifted against the force of a spring 13 by means of a cam 14 when the handle 1 is rotated to an attitude that approximately crosses at right angles to a fixed before-and-behind directional attitude when altering the attitude of the handle 1, a shift fork operation tool 3A, to which upper end portion a non-operation end portion of a speed change lever 5 is connected, a pair of cam surfaces 17, 17, which oscillation guide the operation tool 3A to a speed change neutral attitude when the moving portion material 15 downward moves, and projections 18, 18.