In a gyro which has a ring resonator type laser diode, and which detects a beat signal attendant on rotation, a plurality of laser diodes are disposed on an identical substrate, thereby to exhibit a wide detection range for angular velocities. In the gyro, active layers of the laser diodes may be arranged separately from one another. A semiconductor device includes a plurality of ring resonator type laser diodes, each of which undergoes a voltage change or a change in a driving current in attendance on a magnitude of an applied angular velocity when subjected to constant-current drive, and which are disposed in a single frame or on a single substrate. In the semiconductor device, the ring resonator type laser diodes may be disposed on an identical surface of the single substrate.