Abstract: A polyimidesiloxane film having a low heat conductivity without damaging the heat resistance intrinsic of polyimide, a high hardness and a superior adherence onto its substrate, is provided, which polyimidesiloxane film comprises a cross linked copolymer having repetition units expressed by the formula (1): ##STR1## wherein R.sup.1 independently is a tetravalent organic group, R.sup.2 independently is a divalent organic group of 2 to 30 C, R.sup.3 independently is represented by 4 specified formulas, R.sup.4 and R.sup.5 each are a specified organic group, and n, p, q, and r each have a value within a range satisfying 3 specified equations, and which film exhibited a heat resistance of 511.degree. C. or higher, a hardness of 3H or higher and a heat conductivity of 0.160 or lower.