To provide a longer lasting diamond wheel capable of achieving a high-quality substrate while minimizing the occurrence of chipping occurring when machining the inner periphery of the substrate.

The diamond wheel 1 is composed as follows. Five or more machining grooves, to which diamond grains are anchored, are formed to a base metal 3. The base metal is composed so that its outer diameter D is ≤10 mm and a ratio (L/D) between the length L and the outer diameter D is ≥2 and ≤50. The material of the base metal is composed of cemented carbide including WC particles having an average particle size of ≤2 μm.