To provide a rod for rock drill having a hard surface layer portion by surface hardening treatment and also having a high internal toughness that is, a decrease in the hardness is gentle from the surface layer to which surface hardening treatment is applied to the central portion and the depth (width) of a hardness inclination layer formed between the surface layer portion and the central portion is increased for the rod of rock drill and used.

A mean hardness HS for a predetermined surface layer portion A and a mean hardness Hl for a central portion C are provided, an alloy steel containing Ni, Cr, Mo, and Mn at predetermined proportions are constituted, and the hardness distribution curve at the hardness inclination layer B is expressed in such a manner that the rate of change of mean hardness at (HU-HL)/t2 at the hardness inclination layer B has a value smaller than 450 [HV0.3/mm]. A decrease in the hardness from the surface layer portion A to the central portion C is gentle, and the depth (width) of the hardness inclination layer B formed between the surface layer portion A and the central portion C is large (wide) and thus a rod 100 for rock drill having an excellent abrasion resistance and a high fatigue strength can be obtained.