A cooling device for a vehicle motor comprises a rotation shaft rotatably supported by a casing assembly, a rotor fixed to the rotation shaft, a stator disposed around the rotor and fixed to the casing assembly, a coil wound around the stator, an oil pump motor disposed at a lower portion of the casing assembly, an oil passage faced to the coil and formed in an upper portion of the casing assembly, a cooling fin formed on a side wall of the casing assembly, a separator plate being in contact with the cooling fin, an oil passage cover combined with the separator plate to form an oil passage therebetween, and a cooling fin formed on the oil passage cover.