A Japanese version of the Self-Compassion Scale (SCS-J) was developed. In Survey 1, confirmatory factor analysis of data from participants indicated that the SCS-J had an acceptable fit to the model, as well as good internal consistency, similar to the original. In Survey 2, a test–retest correlation of the SCS-J for 101 participants indicated good reliability for the scale. In Survey 3, 148 participants completed the SCS-J and the Narcissistic Personality Inventory, the Subjective Happiness Scale, the State-Trait Anxiety Inventory-Trait form, and the Beck Depression Inventory. The partial correlations between the SCS-J and the other scales were analyzed, using self-esteem, or self-criticism as the control variables. The results demonstrated that self-compassion was associated with self-esteem and the mental health of the Japanese participants. These results indicate that the SCS-J has good reliability and validity as a measure of self-compassion.