The International Parkinson and Movement Disorder Society (MDS)-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) has been developed and is now available in English. Part of the overall program includes the establishment of official non-English translations of the MDS-UPDRS. We present the process for completing the official Japanese translation of the MDS-UPDRS with clinimetric testing results. In this trial, the MDS-UPDRS was translated into Japanese, underwent cognitive pretesting, and the translation was modified after taking the results into account. The final translation was approved as the Official Working Draft of the MDS-UPDRS Japanese version and tested in 365 native-Japanese–speaking patients with PD. Confirmatory analyses were used to determine whether the factor structure for the English-language MDS-UPDRS could be confirmed in data collected using the Official Working Draft of the Japanese translation. As a secondary analysis, we used exploratory factor analyses to examine the underlying factor structure without the constraint of a prespecified factor organization. Confirmatory factor analysis revealed that Comparative Fit Index for all parts of the MDS-UPDRS exceeded the minimal standard of 0.90, relative to the English version, and therefore the Japanese translation met the prespecified criterion to be designated, called an official MDS translation. Secondary analyses revealed some differences between the English-language MDS-UPDRS and the Japanese translation; however, these differences were considered to be within an acceptable range. The Japanese version of the MDS-UPDRS met the criterion as an Official MDS Translation and is now available for use (www.movementdisorders.org).