PURPOSE: To obtain laser devices which set the desired mode of emitted laser beam adequately, by arranging them on a radiator so that semiconductor laser elements have an uniform array on a well symmetric pattern in case of projection in a laser-beam optical axis direction.

CONSTITUTION: A power source 1 supplies electric power to semiconductor laser elements 2 to achieve laser oscillation. Under the control of a control circuit 8, the supply current from the power source 1 to the elements 2 arrayed on a radiator 3 is controlld. Then, laser beam 7 emitted from the elements 2 are made into one by a condensing and correcting optical system 5, whose output is guided to a light guide 6. With said constitution, S output currents are determined by the circuit 8 to set laser beam, synthesized by (n) semiconductor lasers, nearly in mode TEM00. To obtain laser beam in rectangular mode, the S output currents are equalized by the circuit 8. Further, when a variable bias is applied to the power source 1, the output of the composite laser beam is varied while the S currents are fixed, namely, while the intensity distribution of the laser beam synthesized by the emitted laser beam is held constant.