A control method for a vehicle transmission includes, in a TCU, receiving the rpm of an engine from an rpm sensor and determining whether to perform shifting of gears depending on the received rpm, when the shifting of gears is determined, allowing the TCU to control an ECU to cut off fuel supplied to the engine combustion chamber and to release a clutch connecting the engine and the transmission, after the control action is performed, monitoring a change in pressure of engine cylinders and allowing engine braking action to be activated, and when the rpm is reduced to a predefined value or less after the engine braking action, performing a shifting action.