Aim: Few studies have investigated the health-related quality of life (HRQoL) in longstay inpatients with chronic schizophrenia in Japan. This study aimed to clarify the factors associated with HRQoL among these patients.Methods: Out of 238 patients with chronic schizophrenia admitted to three hospitals, 101 inpatients provided informed consent to participate in the study. The patients' HRQoL was assessed using two instruments: the EuroQol 5 dimensions (EQ-5D) as a generic index and the Subjective Well-being Under Neuroleptic Treatment Scale, Japanese Version (SWNS-J) as a disease-specific index. We examined the factors associated with these HRQoL indices using multiple linear regression models.Results: The patients' mean age was 62.9 years, and 51.5% were female. The mean (standard deviation) EQ-5D score and SWNS-J total score were 0.776 (0.177) and 83.5 (16.5), respectively. Multiple linear regression analysis indicated that the EQ-5D score was significantly and negatively associated with the female sex, benzodiazepine use, and Drug-Induced Extrapyramidal Symptoms Scale scores.In contrast, the SWNS-J total score was significantly and negatively associated with first-generation antipsychotics use, Brief Psychiatric Rating Scale scores, Drug-Induced Extrapyramidal Symptoms Scale scores, and Global Assessment of Functioning scale scores. Conclusion:This study identified the factors associated with two HRQoL indices among long-stay inpatients with chronic schizophrenia in Japan. Although the analyses showed differences in the associated factors between the generic EQ-5D and the disease-specific SWNS-J, extrapyramidal symptoms as adverse effects of antipsychotic treatment were found to be associated with both indices.