In design and construction of off-shore structures on the deep sea, it is absolutely necessary to obtain accurate information on the engineering properties of subsoil. A new apparatus, Marine Auto Sampler-73(MAS-73) was developed and already reported by the authors previously. MAS-73 performed quite well, however, observation of the continuous soil profile was impossible as is usually the case by the thin wall sampling.
　Improvement of the MAS-73 is tried and MAS-76 is developed in the present project. Foil sampler is applied to the apparatus to take long contiinuous sample of 5.0m in length. Compact and high water pressure proof hydraulic unit is developed to increase the working depth and to reduce the size and weight of the overall apparatus.
　By the field experiment of MAS-76 even the extremely weak sub-surface deposil is successfully recovered and soil test results show the good quality of the recovered sample.