The present technology relates to a data processing apparatus and a data processing method which can enhance multipath propagation resistance.When performing modulation processing on a physical layer frame including a preamble, which includes a modulation parameter, and one or more subframes, which include data, the data processing apparatus can set any modulation parameter for each subframe, and the modulation parameter has a relationship of Tui/Dxi≥Tui+1/Dxi+1 in a case where an effective symbol length indicating a length of an effective symbol is Tui and an interval between pilot signals in a frequency direction is Dxi in an i-th (i is an integer equal to or greater than 0) subframe. The present technology can be applied to, for example, data transmission compliant to a broadcast standard such as ATSC 3.0.