A shift position detecting device that determines a shift position based on a detection logic formed of a combination of turning on or off of a plurality of switches that are fixedly arranged at least one by one at positions corresponding to a plurality of detecting object portion rows mounted on a shift drum. An accurate shift position can be detected even if there is an irregularity in switching timings of switching modes of the plurality of switches. A shift position detecting member establishes the shift position as a new shift position and outputs shift position information, while when the detection logic after the transition is a detection logic other than the detection logic corresponding to the changeable shift position, sets the new shift position not yet established and outputs information corresponding to non-establishment of the shift position.