PURPOSE: To provide a collimation optical device in which a light deflecting means is miniaturized and by which collimation is executed with high pointing accuracy.

CONSTITUTION: This collimation optical device is provided with light transmitting optical systems 1 and 2 supplying parallel luminous fluxes, an afocal optical system 10 extending the diameters of the parallel luminous fluxes from the optical systems 1 and 2 and projecting the light to a target, and a light receiving optical system 31 condensing reflected light from the target through the optical system 10; and it is also provided with the light deflecting means 20 arranged in an optical path between the afocal optical system and the light transmitting optical system.