Abstract: A flat belt transmission has two spaced flat pulleys and a flat belt reeved around the flat pulleys. Each pulley can have a plurality of crowns arranged in the width direction of the outer periphery thereof. The flat belt can be a plurality of belts with a narrow width, one for each of the crowns. The flat belt can be a single belt with a part extending in the longitudinal direction of the belt in its inner periphery. The flat belt can be used with the flat pulley of the above construction or a flat pulley having a single crown of its outer periphery. In addition, the plurality of crowns are formed on the outer periphery of the flat pulley so as to be spaced at the same distance from the center of rotation of the pulley, or the outer periphery of the flat pulley can be in the form of a circular arc to change height of the crowns.