Lunar surface is, in spite of disadvantages on payload compared with those in the distant orbits, extremely attractive for future astronomical observations with large and complicated observing instruments. The Moon will provide firm and large base, very stable temperature and low background in some selected sites. In addition, the aids of human activities on the Moon can be expected in the near future. We have been discussing the small but realistic steps toward the future Moon-based astronomy, as part of Japanese lunar exploration plans with HI rockets. The fundamental Policy of Japan’s Space Development which was approved by Space Activities Commission in 1996 described that Japan will continuously promote unmanned lunar exploration and study the feasibility of a systematic exploration program for science and possible activities on the Moon, under a phase-by-phase approach. The plan includes a possibility of astronomical observations on the lunar surface.

Some pilot-type astronomical plans, starting from very small-size telescopes in optical/IR and mm-wave etc. are under discussion. We report here on the general background, discussion including proposed plans, and steps toward the future moon-based observatories.