A cable guide which has a simple structure and can be easily assembled is adapted to change the direction of the inner cable which slide and drive the slide door of a vehicle, and includes a pulley case 11 whose upper surface is opened, a pulley 12 housed in the pulley case and pivoted rotatably, and a case cover 13 to cover the upper surface of the pulley case. The pulley case has a fixing portion 15 of the outer casing which slidably houses an inner cable. The fixing portion has grooves of roughly U-shaped cross section. The inner perimeter of the groove has a case protrusion 15a. A cover protrusion 13e is formed in the case cover so as to face the case protrusion.