CHAIN GUIDE ASSEMBLY FRAME

To provide a simple-structured chain guide assembly frame capable of reliably maintaining a correct positional relationship between a driven sprocket and a sprocket holding portion without the possibility of driven sprocket detachment even when the tension acting on the chain is insufficient. The chain guide assembly frame includes a main body having a fixed-guide-side sprocket holding portion and a pivotingguide-side sprocket holding portion. The fixed-guide-side sprocket holding portion includes a first fixed-guide-side support portion that supports a driven sprocket at a first contact point, and a second fixed-guide-side support portion that supports the driven sprocket at a second contact point located more outside than the first contact point. When the driven sprocket is in an erected state in which the driven sprocket is supported at the first contact point and second contact point, the vector of gravity acting on the gravity center of the driven sprocket points between the first contact point and second contact point.