To provide a cutting device for a tunnel wall surface capable of cutting at a certain depth of a tunnel without using any complicated and expensive system for the tunnel wall surface having a complicated and indeterminate section.

A stopper 25 having a contact face 26 with a diameter smaller than the outside diameter of a cutting tool 19 on the outside of the end face of the cutting tool 19 projected to a radial direction is provided to a slewing shaft 11. The contact face 26 is contacted to the surface TA of a cutting finished part in the tunnel or the surface TB of an uncut part, and the surfaces TA and TB are used as rulers to move the cutting tool 19 to the circumferential direction of the tunnel to execute the cutting of a certain depth of the tunnel.