This study aims at clarifying the human leukocyte antigen haplotypes and genotypes conferring susceptibility or resistance to type 1 diabetes in the Japanese population. The frequencies of human leukocyte antigen DR-DQ haplotypes and genotypes were compared between 83 type 1 diabetic patients, except for fulminant type 1 diabetes, and control subjects in the Japanese population. The patients were divided by onset age into four groups (ages 5–14, 15–29, 30–49, and 50–71 years); the haplotype frequency was compared between each group. The frequencies of DRB1* 0405-DQB1* 0401 (DR4), DRB1* 0802-DQB1* 0302 (DR8), DRB1* 0901-DQB1* 0303 (DR9), and DRB1* 1302-DQB1* 0604 (DR13) haplotypes were significantly higher in the patients than in the control subjects. The frequencies of DRB1* 1501-DQB1* 0602 and DRB1* 1502-DQB1* 0601 haplotypes were significantly lower in the patients than in the controls. The frequencies of DR4/8, DR4/13, DR9/9, and DR9/13 genotypes were significantly higher in the patients than in the control subjects. The DR13 haplotype was the most frequent haplotype in the age group 30–49 years, whereas the other haplotypes but DR13 were the most frequent in the other age groups. DR4, DR8, DR9, and DR13 haplotypes confer susceptibility to type 1 diabetes in Japanese patients.