Clubroot resistance (CR) against the Ano-01 isolate of the clubroot pathogen Plasmodiophora brassicae for individual radish chromosomes was evaluated using 9 types (a–i) of Brassica napus–Raphanus sativus monosomic addition lines (MALs) produced from the progenies of the hybridization of B. napus (2n = 38, AACC) and Raphanobrassica ‘Rb-63’ (2n = 36, RRCC). Among the 9 types of MAL, the c-type showed high resistance, although other types and reverted plants with somatic chromosomes like B. napus (2n = 38) were susceptible. This result suggested that a major CR gene against the Ano-01 isolate may be located on the radish c-chromosome. However, it was also assumed that there might be other CR gene(s) in radish because many c-type MAL plants showed slight disease symptoms.