A cutting-edge replaceable cutting tool comprising: a plate-like cutting insert comprising upper and lower opposite surfaces (11, 13) and a side surface extending between the upper and lower surfaces; a body including an insert mounting portion for removably mounting the cutting insert, the insert mounting portion having a base surface for supporting the lower surface of the cutting insert and a sidewall surface (21B, 21C) for supporting the side surface of the cutting insert; and a reception mechanism configured to receive a rotational moment, the rotational moment acting on the cutting insert so as to rotate the cutting insert mounted on the insert mounting portion on the base surface, wherein the reception mechanism includes a first engagement portion formed on the lower surface of the cutting insert and a second engagement portion formed on the base surface of the insert mounting portion, and wherein the second engagement portion is formed to engage with a specific portion, of a surface defining the first engagement portion, to receive the rotational moment, characterized in that the sidewall surface of the insert mounting portion includes a first sidewall surface facing an outer peripheral side of the cutting-edge replaceable cutting tool and a second sidewall surface facing a leading end side of the cutting-edge replaceable cutting tool, wherein an abutment portion in the second engagement portion for abutting on the first engagement portion is formed in a first region at an opposite side of the first sidewall surface side, of two regions in the base surface divided into two by a first virtual plane extending in a longitudinal direction of the body, the first virtual plane being orthogonal to the base surface and passing a center of the upper surface of the cutting insert mounted on the insert mounting portion, and wherein the abutment portion in the second engagement portion is formed in a second region positioned at the second sidewall surface side of two regions in the first region divided into two by a second virtual plane that is orthogonal to the first virtual plane and passing the center of the upper surface of the cutting insert mounted on the insert mounting portion. a plate-like cutting insert comprising upper and lower opposite surfaces (11, 13) and a side surface extending between the upper and lower surfaces; a body including an insert mounting portion for removably mounting the cutting insert, the insert mounting portion having a base surface for supporting the lower surface of the cutting insert and a sidewall surface (21B, 21C) for supporting the side surface of the cutting insert; and a reception mechanism configured to receive a rotational moment, the rotational moment acting on the cutting insert so as to rotate the cutting insert mounted on the insert mounting portion on the base surface, wherein the reception mechanism includes a first engagement portion formed on the lower surface of the cutting insert and a second engagement portion formed on the base surface of the insert mounting portion, and wherein the second engagement portion is formed to engage with a specific portion, of a surface defining the first engagement portion, to receive the rotational moment, characterized in that the sidewall surface of the insert mounting portion includes a first sidewall surface facing an outer peripheral side of the cutting-edge replaceable cutting tool and a second sidewall surface facing a leading end side of the cutting-edge replaceable cutting tool, wherein an abutment portion in the second engagement portion for abutting on the first engagement portion is formed in a first region at an opposite side of the first sidewall surface side, of two regions in the base surface divided into two by a first virtual plane extending in a longitudinal direction of the body, the first virtual plane being orthogonal to the base surface and passing a center of the upper surface of the cutting insert mounted on the insert mounting portion, and wherein the abutment portion in the second engagement portion is formed in a second region positioned at the second sidewall surface side of two regions in the first region divided into two by a second virtual plane that is orthogonal to the first virtual plane and passing the center of the upper surface of the cutting insert mounted on the insert mounting portion.