A semiconductor laser gyro including a photodetector and a semiconductor laser 10 that emits first and second laser lights. The photodetector is disposed in a position where interference fringes are formed by the first and second laser lights. The semiconductor laser 10 includes an active layer as well as first and second electrodes 13 and 14 for injecting carriers into the active layer. The first laser light is one obtained through emission of a part of laser light (L1) that circulates on a polygonal path in the active layer. The second laser light is one obtained through emission of a part of laser light (L2) that circulates on the polygonal path in the opposite direction to the laser light (L1).