PROBLEM TO BE SOLVED: To provide a measurement device capable of accurately measuring a penetration depth of a penetration probe into a water bottom ground.SOLUTION: On a water bottom ground penetration depth measurement device 20, a cross frame 27 is fixed on an upper end side in a longer direction of a penetration probe 21 to be inserted to the water bottom ground and an underwater video camera 29 is fit to each arm part. A water bottom detection member 30 that can relatively move is fixed near a cone on a tip side of the penetration probe 21. A ring-shaped plate 31, which is fastened to a surface of the water bottom ground when the penetration probe 21 is penetrated, is formed at a lower part of the water bottom detection member 30. A luminescent LED is fit as a gage mark 33 on a top face of the plate 31 at angular interval of 90 degrees. A three-dimensional position information depending on change in a distance between the underwater video camera 29 and the gauge mark 33 is obtained by photographing the g
