To provide a bedrock surface cutting device capable of lowering cutting performance over a long period, lessening wear of a cutting tool and making a traveling machine body lightweight without making the holding member of the cutting tool a specific firm structure and without particularly strengthening a press cylinder.

Crawlers 3, 4 are disposed on the lower side front part and rear part of a traveling machine body 2, and a cutter head 19 mounting a plurality of roller cutters 12 on the lower side intermediate part of the traveling machine body and rotating in almost parallel to a bedrock surface is disposed. In the case, the cutter head 19 may be provided in the form of a disc, may laminate the disc whose outer diameter is small toward downward in order, the roller cutter 12 is preferably multi-staged on the peripheral face part of the cutter head 19 in the axial direction at a prescribed interval, and preferably disposed in each stage in the circumferential direction at a prescribed interval.