A heat-resistant polyether having a heat resistance to a temperature of 300° C. or higher, sufficient solubility in organic solvents, low water absorption and high adhesion to substrates is provided by a heat-resistant polyether including a repeating unit represented by the formula (1) and having a polystyrene-converted weight-average molecular weight determined by GPC of not less than 1000 and not more than 50000: wherein Ar represents a bivalent organic group having an aromatic ring; R1 to R8 each independently represent a hydrogen atom or an aryl group which may be substituted; and when at least one of R1 to R8 is an aryl group which may be substituted, X represents a direct bond or a hydrocarbon group having 1 to 20 carbon atoms, while when all of R1 to R8 are hydrogen atoms, X is represented by the formula (2): —CR9(R10)—  (2) wherein R9 and R10 each independently represent an aryl group which may be substituted.