A depth measurement device includes a guide, a sliding part, a central column and a limit assembly, wherein the guide has a tubular structure. The sliding part is slidably connected to the guide, has a sliding direction parallel to an axial direction of the guide, and is used for connecting a tracer. The central column penetrates through the tubular structure, is able to move in the axial direction and to rotate around an axis, has one tail end for connecting with a cutting tool and another tail end for connecting with a power input. The limit assembly is fixed to the central column, is located on a side of the sliding part adjacent to the other tail end of the central column, and is able to drive the sliding part to synchronously move when moving along with the central column. A grinding device includes the depth measurement device.
