Field and laboratory experiments were conducted to measure the shear modulus profiles in the seabed at the port of Kawasaki located at Kanagawa prefecture, Japan. In the field exploralion, the recently developed Bottom Shear Modulus Profiler (BSMP) was applied to very soft alluvial clay and loose sand layers. The Downhole Method (DM) and the Standard Penetration Test (SPT) were also used to crosscheck the results of the BSMP measurement. In addition, undisturbed clay samples were taken from the investigation site and the shear modulus was evaluated in the laboratory using the Cyclic Triaxial Test (CTT) and the Unconfined Compression Test (UCT). The shear modulus profiles obtained from five different measurements are compared with each other and the applicability of the BSMP is discussed. THe BSMP results for a soft alluvial clay and a sand deposit show good agreement with those from the DM and SPT, especially at shalow depths in the seabed.