To provide a crosslinked rubber which is reduced in electric resistance value, with the rise of the electric resistance value being suppressed even in continuous use, and further has low hardness and excellent compression set resistance.

A crosslinked rubber is obtained by crosslinking a rubber composition including 0.01-20 pts.wt. of a metal oxide relative to 100 pts.wt. of a polyether rubber containing 0.1-30 mol% of a unit represented by general formula (1). (In general formula (1), X^- is an optional counter anion).