  We review recent developments of soliton theories and integrable systems on
noncommutative spaces. The former part is a brief review of noncommutative
gauge theories focusing on ADHM construction of noncommutative instantons. The
latter part is a report on recent results of existence of infinite conserved
quantities and exact multi-soliton solutions for noncommutative Gelfand-Dickey
hierarchies. Some examples of noncommutative Ward's conjecture are also
presented. Finally, we discuss future directions on noncommutative Sato's
theories, twistor theories and so on.
