Provided is a 3-dimensional measuring device capable of eliminating necessity of shutter switching operation, and securing relatively wider measuring range. A 3-dimensional measuring device 1 includes: a light source unit 31 that emits a range-finding light 35; a projection optical system 33 that radiates the range-finding light 35 to a range-finding optical axis 32; a scanning mirror 7 that is provided to be rotatable about a rotating shaft 6 in a state of being inclined with respect to a shaft center of the rotating shaft 6 to radiate the range-finding light 35 within a plane crossing the rotating shaft 6 in a rotary manner; a light-receiving optical system 41 that receives the reflection range-finding light 37; a reference light optical system 24 that is provided in a range outside a measuring range within a radiation range to receive and reflect the range-finding light 35 reflected from the scanning mirror 7 as an internal reference light 36, the reference light optical system being capable of changing a light quantity of the reflected internal reference light 36; and a light receiving element 42 that receives the reflection range-finding light 37 and the internal reference light 36 guided from the reference light optical system 24.