John McEnroe was the defending champion but lost in the semifinals to Stefan Edberg.
Edberg won in the final 6–3, 2–6, 6–4 against Ivan Lendl.
Seeds The top eight seeds received a bye to the second round.
Draw
Finals
Top half
Section 1
Section 2
Bottom half
Section 3
Section 4
External links 1989 Suntory Japan Open Tennis Championships draw