An optical axis restriction surface, which restricts movement of a first lens frame in an optical axis direction, and a fixing slit, which is located in rear of the optical axis restriction surface, are formed on an end portion of a second lens frame. Lens frame hold portions, which restrict rotation of the first lens frame about an optical axis and movement of the first lens frame in a right-and-left direction, are formed on both sides of the fixing slit. The lens frame hold portions are provided with assembly reference surfaces which restrict movement of the first lens frame in an up-and-down direction. An engaging portion, which is engaged with the fixing slit, and two projection portions, which come in contact with the assembly reference surfaces, are formed on the first lens frame.