A valve apparatus for a vehicle includes a housing having open and closed ends to form an interior space, and formed with first and second intake ports receiving a transmission fluid from a transmission and an oil cooler, a bypass port bypassing the transmission fluid to the transmission, and an exhaust port exhausting the transmission fluid to the oil cooler, an inner cap inserted at least partially into the interior space, fixed to the housing, and having an open hole inserted into the interior space, an operation unit disposed between the inner cap and the closed end of the housing, and reciprocally moves according to a transmission fluid temperature, a valve unit disposed in the operation unit to selectively open and close the bypass port and the exhaust port depending on a movement of the operation unit; and an elastic member interposed between the inner cap and the operation unit.