A chain transmission device for driving camshafts includes a chain including a loose side chain portion, and the chain is trained around the crank sprocket and the cam sprockets. A chain guide is mounted on the outer side of the loose side chain portion so as to be pivotable about one of the two end portions of the chain guide, and the chain guide has a plurality of rotatable rollers. An adjustment force is applied to the other of the two end portions of the chain guide by a chain tensioner such that the chain guide is biased toward the chain, so that the rollers of the chain guide can guide the chain by rolling. The winding angle of the portion of the chain located on the outer periphery of the roller located closest to the crank sprocket is set to be 170 degrees or greater so as to reduce noise.