A radio-communication device performs processing in a communication environment in which an OFDM (Orthogonal Frequency Division Multiplexing) modulation method is used. The radio-communication device includes a signal-reception unit that receives a MIMO (Multi Input Multi Output) signal, a data-decoding unit that decodes the MIMO signal, and a data-processing unit that processes data decoded by the data-decoding unit. The radio-communication device also includes a format-determination unit that determines, based on a relative phase difference between a previous packet field and a subsequent packet field adjacent to the previous packet field, a packet format of the MIMO signal. Further, the radio-communication device includes a control unit that stops an operation of the data-decoding unit when the data-processing unit does not support the packet format, which is determined by the format-determination unit. The operation is performed in a field that comes after a field at which the format-determination unit determines the packet format.