The National Metrology Institute of Japan (NMIJ) of the National Institute of Advanced Industrial Science and Technology (AIST) maintains the pressure standards for Japan, which have been established using the most-advanced technology, and disseminates them to industry and society. NMIJ is also conducting various activities, mainly concerning research and development to improve and upgrade the standards and the calibration techniques that can support advanced industrial technology, the establishment and improvement of a traceability system for the standards in Japan, and the checking of the international equivalence of the standards. In this article, the pressure standards, the calibration principles and methods, NMIJ calibration services, the traceability system in Japan and the activities for improving the reliability of the pressure standards are described.