A wheel-state obtaining apparatus for a vehicle, including wheel-side devices (10 16) each having an air pressure sensor (32) for detecting an air pressure of a wheel tire of the vehicle, and a body-side device (18) having receiver antennas (20 26) and arranged to receive wheel-side information from the wheel-side devices through the receiver antennas and extract air-pressure information representative of the detected air pressure, that is, detected-air-pressure information, and wherein the body-side device includes an estimating portion (54) which is operable, in the event of a failure of any of the receiver antennas to receive the wheel-side information, to estimate the tire air pressure on the basis of detected speeds of the wheel, and obtain estimated-air-pressure information representative of the estimated air pressure. Thus, the wheel-state obtaining apparatus is capable of obtaining information on the air pressure even in the event of a failure of the receiver antennas (20 26) to receive the wheel-side information.