A medium cutting device cutting a continuous medium carried along a carrying path in a carrying direction includes a sandwiching part that is provided capable of sandwiching a medium; and a cutting blade that includes an edge extending in a width direction (X) of the medium, which is perpendicular to the carrying direction, wherein the medium is cut by the edge while the medium is sandwiched and held by the sandwiching part. Wherein the edge is in a shape depicting an involute curve in which path lengths (PL) of the medium, which are determined from the sandwiching part to the edge in the carrying direction, are substantially constant over the edge in the width direction.