The chain guide mechanism includes a slack side guide, a tension side guide, and a link member that is capable of rotating about a predetermined rotary shaft provided so as to be fixed to an attachment subject. The link member includes a slack side pivot portion attached rotatably to the slack side guide, and the slack side pivot portion is disposed on an opposite side of the chain that is guided by the slack side guide to the predetermined rotary shaft, and in a lower position than the predetermined rotary shaft. The slack side guide is biased by its own weight toward a side of the chain that is guided by the slack side guide.