An optical power splitter is provided that can stably operate even when there is a mode mismatch between an input optical signal and the optical power splitter. The optical power splitter of the present invention includes a semiconductor substrate, an optical waveguide stacked on the semiconductor substrate, and a clad surrounding the optical waveguide. The optical waveguide includes an input waveguide section through which the optical signal is input from an outer waveguide, a tapered waveguide section having a gradually increasing width, first and second waveguide branches extending from an output end of the tapered waveguide section and outputting first and second branched optical signals, and a stabilizing waveguide section disposed between the input waveguide section and the tapered waveguide section, the stabilizing waveguide section having length and width capable of stabilizing shaking of the optical signal which is generated by a mode mismatch between the optical signal and the input waveguide section.