A base station apparatus, communication terminal apparatus, communication system, and communication method are provided that enable the data part transmission amount to be increased, that are resistant to frequency selective fading, and that enable a BS with low transmission loss to be selected. An OFDM transmitting apparatus 100 sets a power measurement pilot as one OFDM symbol in one frame, assigns power measurement pilot subcarrier numbers to base station apparatuses, and transmits a power measurement pilot according to common frame timing among the base station apparatuses, and a communication terminal apparatus 200 is equipped with an autocorrelator 210 that outputs a symbol synchronization signal, an autocorrelator 220 that finds an autocorrelation characteristic of a repeat waveform part that is a repetition of the same waveform having a cycle of ½ effective symbol length or a waveform with the sign reversed having a cycle of ½ effective symbol length from a received power measurement pilot, and an in-phase averaging section 230 that performs in-phase averaging in frame units of an autocorrelation characteristic of the repeat waveform part and detects the positional frame timing of a power measurement pilot on the time axis.