The development of HF radar for the measurement of the ocean surface has began in Japan from 1987 by Okinawa Radio Observatory, Communications Research Laboratory. We have developed the method to estimate wave spectra, and measured ocean surface currents. With regard to ocean waves, however, the comparison between radar-estimated ocean waves and in-situ data should be improved further. We have also extended the theory of HF radio wave scattering from the sea surface.It is possible to explain the underestimation of wave heights, which was previously pointed out.The discrepancies between measured and predicted Doppler spectra at higher Doppler frequencies in high sea states are still in problem, although we have attempted to explain the discrepancies. With regard to ocean currents, we will present preliminary results of measurements around Okinawa Island, Japan. The one is the measurement associated with the passage of a typhoon. The other is the measurement of the convergent zone associated with the front of a mesoscale eddy.