To provide a novel settlement measuring apparatus for grasping the settlement of a foundation, in which construction is facilitated and further an expensive pressure sensor is not being buried uselessly but can be utilized over and over again.

A settlement measuring apparatus 20 which grasps the settlement of a foundation comprises a housing 21 which is disposed on the surface of the foundation and filled with water internally, a water conduit 24 which is filled with water and connected to the housing and of which an upper end 24a is extended to the outside of the foundation, fixed at a constant height position and opened in outer air, an airbag 22 disposed within the housing, and a communication pipe 23 of which the lower end is communicated to the airbag and of which the upper end extends to the outside of the foundation. When the foundation is settled, the head pressure inside the housing 21 is increased as a height of the distal end of the water conduit connected to the housing is increased, the airbag is compressed therewith, and a change of pressure in the airbag at that time is measured by a pressure sensor 25 mounted in the upper end of the communication pipe communicated to the airbag.