The present invention aims to provide an intra-oral measurement device and an intra-oral measurement system capable of measuring an inside of an oral cavity at high accuracy without increasing a size of the device, and includes a light projecting unit for irradiating a measuring object including at least a tooth within an oral cavity with light, a lens system unit for collecting light reflected by the measuring object, a focal position varying mechanism for changing a focal position of the light collected by the lens system unit, and an imaging unit for imaging light passed through the lens system unit.