A vehicular wireless transmission apparatus includes a memory that stores (i) a default adjustment value relative to a default vehicle model, (ii) a default vehicle model data indicating the default vehicle model, and (iii) a correction value table for correcting the default adjustment value to be compliant with each of different vehicle models different from the default vehicle model. When a host vehicle model data read from a different ECU does not match with the default vehicle model data stored in the memory, it is determined that the vehicular wireless transmission apparatus is presently mounted in a host vehicle model indicated by the host vehicle model data read from the different ECU. The default adjustment value is then corrected by retrieving a correction value corresponding to the host vehicle model data from the correction value table.