To provide a film forming composition (coating liquid) can form an insulated film with a low dielectric constant, the excellent mechanical strength and a good surface property, and an electronic device using the composition.

The film forming composition includes a polymer of a substituted styrene derivative represented by formula (1), (wherein R1 is a hydrogen atom, an alkyl group or an aryl group, R2 is a hydrogen atom, an alkyl group or an aryl group, R3 is an alkyl group, an aryl group, an alkoxy group, an acyloxy group, an aryloxy group, a hydroxy group, a carboxyl group, an alkoxy carbonyl group, an aryloxycarbonyl group, a trialkylsilyl group or a triarylsilyl group, in the case R3 is present by plurality, they may be either same or different, and they may be coupled with each other to form a ring structure, and n is an integer or 0-4).