An infinitely variable speed converter having at least two dynamo/motors, to reduce the thickness in the direction of the central shaft. A space is provided in a portion surrounded by a rotor arranged to rotate clockwise with either a drive disk or a drive gear, a rotor arranged to rotate counterclockwise with either a drive disk or a drive gear, and a radial interior of a stator formed by annularly disposing field magnets. When a traction roller or a traction gear penetrated by a drive shaft is inserted into the provided space, contacting the drive disk to be subject to a couple and thereby rotating while the traction gear comes into contact with the drive gear, whereby an output can be provided to the drive shaft that penetrates the traction roller or the traction gear, so that the entire structure can be compactified.