A scanner with a detachable mechanism to release jammed paper includes a base a, a pickup roller, a pickup mechanism and a scanning module. The base includes an accommodating space and a feeding slot connected to the accommodating space. The pickup roller is rotatably disposed in the base and positioned between the accommodating space and the feeding slot. The pickup mechanism is disposed in the base and adjacent to the pickup roller. The scanning module is detachably disposed in the accommodating space. The scanning module forces the pickup mechanism against the pickup roller when the scanning module is placed in the accommodating space. A pressure exerted on the pickup roller by the pickup mechanism is released when the scanning module is removed out of the accommodating space.