A position adjustment device for an integration rod includes a fixed plate, two resilient members, and two adjusting screws. The first resilient member is positioned between the fixed plate and the rod for exerting an elastic force on the rod in a first direction, and the second resilient member is positioned between the fixed plate and the rod for exerting an elastic force on the rod in a second direction different from the first direction. The first adjusting screw is inserted through the part of the housing and has a first end surface that presses against one side surface of the rod opposite the first resilient member. The second adjusting screw is inserted through the part of the housing and has a second end surface that presses against one side surface of the rod opposite the second resilient member. The first and the second end surface are arc surfaces.