During a period in which a clutch is in a partially engaged state at the time of start of a vehicle, a transmission ECU calculates load acting on the clutch (clutch-absorbed energy). When this load is large, generation of a shift signal based on a gear shift map is prohibited, and the initial gear position is held. The clutch-absorbed energy is obtained through integration of the product of clutch transmission torque and the difference between rotational speed of an engine and rotational speed of the clutch. The clutch transmission torque is determined with reference to a clutch transmission torque map provided in the transmission ECU.