Receiving apparatus with waveform degradation compensating function

A receiving apparatus comprises a first waveform degradation compensating unit (3), a second waveform degradation compensating unit (5), a received waveform measuring unit (8) for measuring waveform data on a received signal, a control unit (9) for controlling compensation characteristics of the first and second waveform degradation compensating units (3, 5) to minimize a difference between frequency data obtained by converting the obtained received waveform data into a frequency domain and frequency data on a reference waveform free from waveform degradation, and time-constant generating units (16-1, 16-2) for making a difference in compensation characteristic control speed between the first and second waveform degradation compensating units (3, 5). This realizes high-accuracy compensation for waveform degradation of a received signal stemming from chromatic dispersion, polarization mode dispersion or the like without employing a dispersion compensation fiber or a polarization maintaining fiber.