To provide hot tool steel having improved toughness, and to provide its production method.

Regarding the hot tool steel, in hot tool steel comprising, by mass, 0.2 to 0.7% C and 0.5 to 7.0% Cr, the content of Al is regulated to ≤0.04%, and also, the degree in the segregation of Cr in the matrix composition lies within ±0.2 mass%. Regarding the hot tool steel, preferably, the content of Al is regulated to ≤0.015%, or further, the number of aluminum oxides with the maximum diameter of ≤5 μm observed in the cross-sectional structure is ≤2,500 (inclusive of zero) pieces/mm2. In the method for producing the hot tool steel, a steel ingot obtained by a remelting method and having a composition comprising, by mass, 0.2 to 0.7% C and 0.5 to 7.0% Cr, and in which the content of Al is regulated to ≤0.04% and/or a steel slab obtained by subjecting the steel ingot to hot working are/is subjected to homogenizing heat treatment.