An optical element for being carried on a slider moving over a recording medium, the optical element being made of a fluid material that transmits light guided from a light source, the optical element which includes a groove an first end which is open and an second end is closed, and a deflection surface for deflecting a light coming from the aforementioned second end of the groove, wherein the thickness of the aforementioned fluid material forming the bottom of the groove is greater on the second end than on the first end.