We theoretically estimated pK(a) of N-containing heterocycles in DMSO by a quantum chemistry method with a polarizable continuum model, which was previously developed for estimating pK(a) of molecules in water. We numerically show the present scheme also works for DMSO solvent as accurately as for water. According to the obtained result, we confirmed transferability of obtained parameters in calculating pK(a) using Gibbs energy in different solvent conditions.