Heat-resistant composition

A heat-resistant composition containing solvent-soluble polyimide resin (A) and a phosphazene compound (B), wherein

• said phosphazene compound (B) includes at least either a cyclic phenoxyphosphazene compound (B1) expressed in the following chemical formula (1):
• 16
• where m represents an integer of 3 to 25 and Ph represents a phenyl group,
• or a chain phenoxyphosphazene compound (B2) expressed in the following chemical formula (2):
• 17
• where X1 represents group-N═P(OPh)3 or group-N═P(O)OPh, Y1 represents group-P(OPh)4 or group-P(O)(OPh)2, n represents an integer of 3 to 10,000 and Ph represents a phenyl group,
• or a cross-linked phenoxyphosphazene compound (B3) cross-linked by a cross-linking group including at least one of an o-phenylene group, an m-phenylene group, a p-phenylene group and a bisphenylene group expressed in the following chemical formula (3):
• 18
• where A represents —C(CH3)2—, —SO2—, —S— or —O— and a represents 0 or 1, with respect to said phosphazene compound including at least either said cyclic phenoxyphosphazene compound (B1) or said chain phenoxyphosphazene compound (B),
• so that said cross-linking group intervenes between two oxygen atoms desorbed by said phenyl group of said phosphazene compound and the phenyl group content is 50 to 99.9% with reference to the total number of phenyl groups contained in said phosphazene compound including at least said cyclic phenoxyphosphazene compound (B1) or said chain phenoxyphosphazene compound (B2) with no free hydroxyl groups in molecules.