Provided are an imaging device and a monitoring device capable of accurately measuring a distance and a shape of a region of an object that is difficult to measure by one distance measuring camera.
Provided is an imaging device including a sensor unit configured to irradiate an object with light and detect the light reflected by the object; a distance calculation unit configured to calculate a distance to the object on the basis of sensing data of the sensor unit; a specular reflector located on an opposite side of the sensor unit across the object; and a correction unit configured to correct an error included in the calculated distance, the error being caused by an interference between the light following a first path from the sensor unit toward the object and the light following a second path from the sensor unit, reflected by the specular reflector, and going toward the object.