A control apparatus (100; 140) for a vehicle transmission that includes (i) a shaft , (ii) a plurality of transmission gears which are disposed on the shaft , (iii) a switching mechanism which is disposed to be adjacent to one of the transmission gears in an axial direction of the shaft and which is to be switched between a connecting state in which the one of the transmission gears is rotatable integrally with the shaft and a disconnecting state in which the one of the transmission gears is rotatable relative to the shaft , (iv) a shift fork which is configured to move the switching mechanism in the axial direction and (v) a shift barrel that is to be rotated to position the shift fork in a position that is dependent on a rotation angle (θbrl) of the shift barrel , in the axial direction, wherein the switching mechanism includes (iii-1) first and second rings which are disposed on the shaft so as to be arranged in the axial direction and which are unrotatable relative to the shaft and movable relative to the shaft in the axial direction and (iii-2) an elastic member which is disposed between the first and second rings in the axial direction and connects the first and second rings , wherein said control apparatus (100; 140) comprises a failure determining portion (122; 152) configured to determine that a failure occurs in the vehicle transmission , when a reaction-force-related value (L) related to a reaction force that acts on the shift barrel during rotation of the shift barrel is deviated from a predetermined range (Lmin-Lmax), wherein said failure determining portion (122; 152) is configured, when determining that the failure occurs in the vehicle transmission , to determine at least one factor of the failure, depending on whether the reaction-force-related value (L) is larger than an upper limit value (Lmax) of the predetermined range (Lmin-Lmax) or is smaller than a lower limit value (Lmin) of the predetermined range (Lmin-Lmax), and wherein said failure determining portion (122; 152) is configured to determine: a) that a breakage of the elastic member , a breakage or wear of the shift fork and/or a breakage or wear of the shift barrel occur in the vehicle transmission , when the reaction-force-related value (L) is smaller than the lower limit value (Lmin) of the predetermined range (Lmin-Lmax); and/or b) that a drawback that the elastic member is not restored from an elastic deformation thereof and/or an increase of resistance against sliding movement of the switching mechanism relative to the shaft occur in the vehicle transmission , when the reaction-force-related value (L) is larger than the upper limit value (Lmax) of the predetermined range (Lmin-Lmax). a) that a breakage of the elastic member , a breakage or wear of the shift fork and/or a breakage or wear of the shift barrel occur in the vehicle transmission , when the reaction-force-related value (L) is smaller than the lower limit value (Lmin) of the predetermined range (Lmin-Lmax); and/or b) that a drawback that the elastic member is not restored from an elastic deformation thereof and/or an increase of resistance against sliding movement of the switching mechanism relative to the shaft occur in the vehicle transmission , when the reaction-force-related value (L) is larger than the upper limit value (Lmax) of the predetermined range (Lmin-Lmax). <EOS>