To provide a rotary cutting tool in which a satisfactory cut state in which burrs and uncut portions are absent is obtained, even when counterboring is applied to a composite honeycomb member. A first cutting-chip discharge groove (2) disposed from a tool tip towards a base-end side is formed on an outer periphery of a tool body (1); a plurality of second cutting-chip discharge grooves (3), provided along a spiral disposed from the tool tip towards the base-end side so as to intersect with the first cutting-chip discharge groove (2), are formed on an outer periphery section of the tool body (1) where the first cutting-chip discharge groove (2) is absent; and a base-end-side outer periphery cutting edge (4) is formed on an intersection ridge between a rake face of a second cutting-chip discharge groove (3), which faces a direction of tool rotation, and an outer peripheral surface of the tool body (1) or an outer peripheral relief face; wherein an end cutting edge (5) is provided at a tip section of the tool body (1); a tip-side outer periphery cutting edge (6) is formed on an intersection ridge between the rake face at a tip section of a first cutting-chip discharge groove (2) and an outer peripheral surface of the tip section of the tool body (1) or an outer periphery relief face (18); and the base-end-side outer periphery cutting edge (4) is provided further towards the tool base-end side than the tip-side outer periphery cutting edge (6).