Institute of Space and Astronautical Science (ISAS), Japan, plans to undertake a lunar mission, named as LUNAR-A, which is to be launched in early 1996. The scientific objective of the mission is to explore the lunar interior using seismometry and heat-flow measurement toward better understanding of the origin and evolution of the moon. The M-V, the newest version of the Mu series launch vehicles now under development, is used to send a 550 kg of spacecraft to the lunar transfer orbit. Three penetrators (which are missile-shaped instrument carriers) are deployed from a spacecraft onto the lunar surface, and constitute a seismic and heat-flow measurement network of a larger span than the Apollo ALSEP network. The present paper describes the outline and scientific implications of the ISAS lunar penetrator mission.