An observation device 1 includes a transmitter and receiver (a transmitter 11, a transmission/reception switch 12, an antenna 13, and a receiver 14) that emits a predetermined radar wave to outside the observation device, and that receives the radar wave scattered by an object existing outside the observation device and acquires a received signal, a temporary image generator 15 that generates a temporary image from the received signal acquired by the transmitter and receiver, and a data transmitter 17 that transmits the temporary image generated by the temporary image generator 15 to a data processing device 2. The data processing device 2 includes a data receiver 21 that receives the temporary image transmitted by the data transmitter 17, and an image generator 24 that generates an image from both the temporary image received by the data receiver 21 and orbit data about a moving object.