I have observed sea clutter containing a target (ship) using an S-band radar with a frequency of 3.05GHz, a beamwidth of 1.8°, a pulsewidth of 0.5µs, and a pulse-repetition frequency of 1,600Hz. To investigate the sea clutter amplitude statistics, I use partial Q-Q plot. I have found that the sea clutter amplitudes obey the Weibull distribution with the shape parameter of c=3.18 for entire data and the Weibull and log-Weibull distributions with the shape parameters of c=3.05 to 4.36 and c=11.84 to 11.95, respectively, for data within the beam width of an antenna. The number of the largest log-likelihood of the Weibull and log-Weibull distributions to data are 9 and 2, respectively, from 11 range sweep numbers. I have used the Weibull/CFAR (Constant False Alarm Rate) circuit which is modified a Cell-Averaging (CA) LIN/CFAR circuit. It is found that ship is detected and sea clutter is suppressed with improvement of 40.82dB by Weibull/CFAR.