A gear position detecting device includes a rotation angle sensor for detecting a turn position of a shift drum and a position sensor for detecting that the shift drum is at a neutral position. The rotation angle sensor is a volume sensor that linearly increases or decreases an output voltage according to a turning motion of the shift drum. The neutral position is set in such a way as not to overlap a dead zone. It is determined according to an output signal of the rotation angle sensor and an output signal of the position sensor whether the shift drum is at a reverse gear position located between the neutral position and the dead zone or a fifth gear position turned by 360 degrees from the reverse gear position. Such detecting device detects a gear position with a high accuracy even if the number of gear positions are increased.