To ensure a minimum necessary total receiving time while shortening the time of receiving work by detecting the state of a receiving radio wave from a satellite and determining the sum of time when the receiving state is good.

A first GPS processing section 12 makes a decision whether a GPS signal received from a satellite has a signal level higher than a predetermined level and indicates a good receiving state when the predetermined level is exceeded. A second GPS processing section 52 indicates a good receiving state when a received CPS signal has a signal level higher than a predetermined level. A first GPS receiving unit 10 detects and indicates that the receiving state of both the first and second GPS receiving units 10, 50 is good and then determines and indicates the sum of time when the receiving state of both the first and second GPS receiving units 10, 50 is good after provision of a survey start command. When the sum of time exceeds a predetermined time, a processor 15 delivers a signal notifying the fact thus ending the survey work.