To provide a water bottom ground depth measuring meter and a depth measuring method capable of easily measuring and improving the measurement accuracy.

A water bottom ground depth measuring meter 1 is used for measuring the water bottom ground depth. It is constituted of a base 2 placed on the water bottom ground, a cylindrical column part 3 stood on the base 2 and at least projecting at the top end from the water surface and having a water path hole 6 underwater and a reference part of which upper end at least is projecting over the upper end of the column part 3. The reference part is constituted by standing a level rod 4A on the upper surface of a float 4B.