A tire inflation pressure sensing apparatus includes a transmitter on a wheel of a vehicle and a receiver on a body of the vehicle. The transmitter includes a pressure sensor working to generate a pressure signal and a charging unit configured to be charged with electrical power via a radio wave from the receiver. The receiver performs a "packet charge" for the charging unit of the transmitter, during which operation of the receiver is changed alternately between an ON-mode and an OFF-mode. When the receiver receives in the OFF-mode an informing signal from the transmitter, it stops the packet charge to receive the pressure signal sent out from the transmitter following the informing signal. The transmitter starts, when the electrical power charged in the charging unit has increased to a predetermined level, to repeatedly send out the informing signal a plurality of times, and then sends out the pressure signal.