To provide an optical axis adjusting method for a multi-optical axis photoelectric safety device capable of arranging a light curtain with narrow intervals between optical axes as near as possible to a pressing machine or the like.

A blanking optical axis shaded by a interfering object 21 is set and optical axes of a main projector 11 and a main photodetector 12 are adjusted by adjusting positions and/or orientations of the main projector 11 and/or the main photodetector 12. Optical axes between the main projector 11 and a sub photodetector 13 are adjusted by finely adjusting a position and/or orientation of the sub photodetector 13. Optical axis between a sub projector 14 and the main photodetector 12 are adjusted by finely adjusting a position and/or orientation of the sub projector 14.