To provide an electronic surveying instrument wherein a main power source is turned ON only by a single key operation and also an arbitrary mode among a plurality of measurement modes is selected and set.

A switch input part 19 monitors an input state of each function key even before a main power source is supplied to a central control part 15. When any function key is pushed down, it is informed to a power source control part 25. The power source control part 25 which receives the information supplies a main power source to the central control part 15. The central control part 15 with the main power source supplied is informed of a key number of the pushed function key from the switch input control part 19 for reading assigned key information with the informed key number written from an EEPROM 21. The central control part 15 reads, from a ROM 23, measurement mode information corresponding to a measurement mode name written in the read assigned key information. The central control part 15 displays a screen contained in the read measurement mode information on a display panel 12, sets respective commands contained in the measurement mode information to corresponding function keys (F1 to F5) respectively, and executes a program whose head address is mentioned in the measurement mode information.