An apparatus for obtaining a 3D image including a light transmitter configured to transmit infrared ray (IR) structured light to a recognized object; an RGB-IR sensor configured to receive infrared rays and visible light reflected from the recognized object; a processor configured to obtain 3D image information including depth information and a visible light image of the recognized object by using each of the infrared rays and the visible light, which are received by the RGB-IR sensor. The processor is further configured to obtain infrared differential images by subtracting infrared images obtained for a visible light measurement time period T1 from infrared images obtained for an infrared measurement time period T2.