A shift position detecting device comprising: a plurality of projection rows (98, 99) each of which includes projecting portions (98a, 98b, 98c; 99a, 99b, 99c, 99d) arranged at a plurality of places in a spaced-apart manner in the circumferential direction of a shift drum constituting a part of a multi-stage transmission having gear trains (G1, G2, G3, G4, G5, G6) of a plurality of shift stages which are selectively establishable, and are mounted on the shift drum; three switches (SA, SB, SC) which are fixedly arranged at least one by one corresponding to the plurality of projection rows (98, 99) such that a switching mode is changed from an OFF state to an ON state by being brought into contact with the projecting portions (98a to 98c, 99a to 99d); and a shift position determining means which determines a shift position by collating the shift position allocated to the detection logic based on the detection logic which is formed of a combination of "1" generated when the switches (SA to SC) are in an ON state and "0" generated when the switches (SA to SC) are in an OFF state, wherein "1, 1, 1" is allocated as the detection logic at a neutral position arranged between a first speed position and a second speed position, wherein the two projection rows (98, 99) which are objects to be detected by the two specified switches (SB, SC; SA, SC) among the three switches (SA to SC) are formed so as to change switching modes of the specified switches (SB, SC; SA, SC) from an OFF state to an ON state and to displace timings at which the specified switches are brought into an ON state from each other when the shift position is changed from at least one of the first speed position and the second speed position to the neutral position, characterized in that the multi-stage transmission is configured such that a shifter (72, 77) is engaged with a gear (62, 68) which constitutes a part of at least one of the first-speed gear train and the second-speed gear train so as to establish at least one of the first-speed gear train and the second-speed gear train, a timing (-α1, α5) at which a switching mode of one specified switch (SB, SA) out of the two specified switches (SB, SC; SA, SC) is brought into an ON state from an OFF state is set on a more neutral position side than switching timings (-α2, -α3, α6, α7) of engagement of the shifter (72, 77) with the gear (62, 68) and releasing of the engagement, and a timing (-α4, α8) at which a switching mode of the other specified switch is brought into an ON state from an OFF state is arranged simultaneously with the switching timing (-α2, -α3, α6, α7) or on a side more away from the neutral position than the switching timing (-α2, -α3, α6, α7). a plurality of projection rows (98, 99) each of which includes projecting portions (98a, 98b, 98c; 99a, 99b, 99c, 99d) arranged at a plurality of places in a spaced-apart manner in the circumferential direction of a shift drum constituting a part of a multi-stage transmission having gear trains (G1, G2, G3, G4, G5, G6) of a plurality of shift stages which are selectively establishable, and are mounted on the shift drum; three switches (SA, SB, SC) which are fixedly arranged at least one by one corresponding to the plurality of projection rows (98, 99) such that a switching mode is changed from an OFF state to an ON state by being brought into contact with the projecting portions (98a to 98c, 99a to 99d); and a shift position determining means which determines a shift position by collating the shift position allocated to the detection logic based on the detection logic which is formed of a combination of "1" generated when the switches (SA to SC) are in an ON state and "0" generated when the switches (SA to SC) are in an OFF state, wherein "1, 1, 1" is allocated as the detection logic at a neutral position arranged between a first speed position and a second speed position, wherein the two projection rows (98, 99) which are objects to be detected by the two specified switches (SB, SC; SA, SC) among the three switches (SA to SC) are formed so as to change switching modes of the specified switches (SB, SC; SA, SC) from an OFF state to an ON state and to displace timings at which the specified switches are brought into an ON state from each other when the shift position is changed from at least one of the first speed position and the second speed position to the neutral position, characterized in that the multi-stage transmission is configured such that a shifter (72, 77) is engaged with a gear (62, 68) which constitutes a part of at least one of the first-speed gear train and the second-speed gear train so as to establish at least one of the first-speed gear train and the second-speed gear train, a timing (-α1, α5) at which a switching mode of one specified switch (SB, SA) out of the two specified switches (SB, SC; SA, SC) is brought into an ON state from an OFF state is set on a more neutral position side than switching timings (-α2, -α3, α6, α7) of engagement of the shifter (72, 77) with the gear (62, 68) and releasing of the engagement, and a timing (-α4, α8) at which a switching mode of the other specified switch is brought into an ON state from an OFF state is arranged simultaneously with the switching timing (-α2, -α3, α6, α7) or on a side more away from the neutral position than the switching timing (-α2, -α3, α6, α7).