A data processing apparatus includes an inputting portion; a first retrieving portion; a second retrieving portion; a clock determining portion; a first serial parallel converting portion; a second serial parallel converting portion; and a combining portion. The inputting portion receives a serial data including a clock bit. The first retrieving portion obtains a first retrieved data. The second retrieving portion obtains a second retrieved data. The clock determining portion determines whether the clock bit is included in the first retrieved data or the second retrieved data. The first serial parallel converting portion performs parallel conversion to obtain a first parallel data. The second serial parallel converting portion performs parallel conversion to obtain a second parallel data. The combining portion combines the first parallel data and the second parallel data to output a parallel data.