Analog sub-bottom profilers (SBPs)are still used in surveys of shallow geological structures below seafloor.Digitized SBPs have various advantages over the analog ones. We tried digitization of a SBP, “SH-20”(Senbon Denki Co.,Ltd.,Japan)in this study.An SBP digitizer,“SonarWiz.SBP”(Chesapeake Technology Inc.,USA),with a high-frequency(62.5kHz max.)sampling rate and a Windows notebook PC were used for the digital recording of received signal. An analog/digital sub-bottom profiling system was constructed by combining the SBP, the SBP digitizer, the notebook PC and a DGPS receiver. A field experiment of digital and analog recording of SBP was carried out around coastal area of Miho Peninsula (Shizuoka, Japan) using R/V “Hokuto”(20tons) of Tokai University. The experimental result clearly showed that the resolution of the digital record was higher than that of the analog one.