This volume contains all the oral and poster sessions presented at the "Numerical Astrophysics 1998" symposium held in Tokyo in March 1998. It covers a wide variety of research fields, from the large-scale structure of the universe to planetary systems. Astrophysics employing all kinds of supercomputers, such as massive-parallel computers, parallel vector machines and special-purpose computers, are included. Animations and full-colour graphics based on computer simulations are presented in an accompanying CD-ROM, which also contains documents written in HTML for brief explanations. Recent progress in numerical methods, remote data analysis and special-purpose computers are also reviewed.