A collimator lens having a low reflectivity and significantly improved durability against high-power light is provided so that optical parts using the collimator lens can be reduced in size and cost lowered. A plurality of optical fibers can be connected to the collimator lens to produce a variety of fiber collimators and optical parts based on the fiber collimator. The collimator lens is made essentially of quarts glass whose refractive index is graded radially so as to increase towards the optical axis and decrease gradually towards the outer periphery. The collimator lens and optical fibers are connected directly by fusion.