To provide an optical clock signal extracting device with a simple configuration, by which an optical clock signal may be extracted without depending on the polarization direction of an input optical signal. A current is injected to a gain region 30 through an n-type common electrode 12 and a p-type electrode 24 in the gain region 30 by a constant current source 28. A reverse-bias voltage is applied by a constant voltage source 26 to a saturable absorption region 32 through the p-type electrode 12 and the n-type common electrode 72 in the saturable absorption region 32. An optical waveguide 16 in the gain region is formed with bulk crystal or a quantum well structure into which extension strain is introduced, and an optical waveguide 18 in the saturable absorption region is formed with a quantum well structure into which extension strain is introduced. Moreover, in the gain region, an optical gain for the TE mode is configured to be larger than that for the TM mode, and, in the saturable absorption region, absorption saturation energy for the TM mode is configured to be smaller than absorption saturation energy for the TE mode.