Provided is a wireless transmitter capable of accurately specifying the number of multiplexed streams and correctly decoding the data signals when a preamble sequence transmitted from any antenna of a wireless transmitter is detected. In this device, a multiplex count determination unit (101) determines the number of streams used by the device itself from the same number of candidates as the number of spatially multiplexed streams. A sequence group generator (104) forms a plurality of preamble sequences into the same number of groups as the number of candidates, which is the number of streams. A sequence group selector (105) selects the group matching the number of streams determined by the multiplex count determination unit (101) from a plurality of groups. A preamble generator (106) selects the same number of preamble sequences as the number of streams in the group selected by the sequence group selector (105) and generates the preamble sequence used by the device itself.