A fixing structure for an optical element includes a first element face of the optical element, a second element face of the optical element which is orthogonal to the first element face, a first positioning plane of a fixed member which abuts with the first element face of the optical element and is fixed on the first element face with an adhesive, and a second positioning plane of the fixed member which is orthogonal to the first positioning plane and abuts with the second element face of the optical element. The second positioning plane is defined by a small projecting part which protrudes from the fixed member perpendicularly with respect to the first positioning plane to abut with the second element face. The fixing structure for an optical element is preferably applied to an optical head device.