The invention provides a segment type diamond tool capable of improving cutting rate and reducing the amount of fine debris generated during cutting by properly arranging diamond particles in a cutting segment of the diamond tool. In the invention, the layers of diamond particles are arranged such that cutting grooves formed on a workpiece by trailing layers of diamond particles are arranged between cutting grooves formed thereon by leading layers of diamond particles, respectively, in cutting of the work piece. The cutting segment has high-concentration and low-concentration areas. The high-concentration area shows a concentration higher than an average concentration and the low concentration area shows a concentration lower than the average concentration. Also, at least one low concentration area is formed on the leading and/or trailing section of the cutting segment. The diamond tool of the invention ensures superior cutting rate and reduced amount of fine debris generated during cutting.