The Cognitive Bias Questionnaire for Psychosis (CBQp) is a valid selfreport instrument for assessing cognitive biases in psychosis. To validate the Japanese version of the CBQp, and to investigate the relationships between CBQp and various schizophrenia symptoms, such as positive symptoms, negative symptoms, and disorganized/autistic preoccupation. Patients with schizophrenia (n = 111), patients with depression (n = 40), and healthy controls (n = 35) were recruited. Using these samples, the psychometric properties of the Japanese version of CBQp were tested. The CBQp total scores had good reliability while the two subscales had moderate reliability. Furthermore, the scales had adequate concurrent validity, given that it had significant correlations with positive symptoms, and could accurately distinguish between schizophrenia patients and healthy controls. Novel findings were that the CBQp total scores were positively correlated with disorganized/autistic preoccupation. Furthermore, this study using a Japanese sample showed marginally significant correlations between the cognitive biases of threating event and severity of delusions, while this relationship was not seen in a previous study that used a Western sample. This difference could be because of the 'shame culture', which is explained as a characteristic of Japanese. The Japanese version of the CBQp was as reliable and valid as the original.