PURPOSE: To obtain a small-sized output detector for laser oscillators which can simultaneously detect the oscillation output of a laser oscillator and position of laser light and has a simple structure as a sensor.

CONSTITUTION: A sensor 3 for detecting output composed of four elements 3A-3D symmetrically arranged with respect to the axis of a partially transmissive mirror 2 faced to an output mirror 1 is provided in parallel with the mirror 2 on the rear side of the mirror 2. An adder/amplifier circuit 4 calculates and amplifies the sum of the output voltages Va-Vd of the elements 3A-3D and displays the amplified sum on a power meter 8 and a differential amplifier circuit 5 respectively amplifies the differences between the output voltages Va and Vb of the elements 3A and 3B arranged in the Y-axis direction and between the output voltages Vc and Vd of the elements 3C and 3D arranged in the X-axis direction and displays the position of laser light on a position meter 9.