To provide a cutting tool capable of highly efficiently and simply cutting a water-retentive resin foam block for flower arrangement.

A plurality of cutter wires S are tensioned between a square frame-shaped guide frame 51, which has a square hole H1 with vertical/horizontal dimensions corresponding to the longitudinal/lateral dimensions X and Y of either one face B1 of the rectangular-parallelepiped water-retentive resin foam block B with a prescribed dimension for flower arrangement, in such a manner as longitudinal and lateral crossing the square hole H1. While being positioned by the guide frame 51, the water-retentive resin foam block B is made to pass through the inside of the square hole H1 and is simultaneously cut in the longitudinal and lateral directions by the cutter wires S.