The invention provides a non-stage transmission which shifts gear in response to a load without requiring any independent actuator for changing a change gear ratio, and can achieve a large change gear ratio on the basis of a small-sized and low-cost structure.The non-stage transmission is structured such that a rocker arm 4 is reciprocated via a connection rod 18, a means for changing a stroke of the reciprocating motion is provided, and an output shaft 2 is driven in one direction whichever of forward and backward directions of the reciprocating motion of the rocker arm 4. An input side turning body 13 is structured such as to drive an output side turning body 14 via an energizing spring 12. The stroke of the reciprocating motion is changed by rotating a crank shaft lever by a cam groove 13d in a clockwise direction in correspondence to an increase of a load so as to shorten a distance between points Q, S. A torque and a rotational number of the output shaft are changed on the basis of a change of the stroke.