A contactlessly measuring system having a contactlessly measuring device, with a light transmitter portion and a light receiver portion, for determining the position of a tool or for determining the longest cutting edge of a rotating tool in a tool machine. A light barrier system is formed by the light transmitter portion and the light receiver portion, each being associated with a leg of an essentially U-shaped support structure of the measuring device. A fluid blowing device, associated with the measuring device, is provided for cleaning a tool to be measured, and/or a sealing air feed is provided in the area of a measuring beam of the measuring device designed as a light barrier measuring system, and/or a protective/closing device is provided at the light transmitter portion and/or the light receiver portion of the measuring device designed as a light barrier measuring system.