Abstract: A resin composition includes a phenoxy resin as a principal component. The phenoxy resin has a weight-average molecular weight of 40,000 or more. The phenoxy resin has, in the same or different molecules, a first structural unit derived from bisphenol S phenoxy and a second structural unit derived from a bisphenol epoxy other than the bisphenol S phenoxy. A content ratio of the first structural unit in the phenoxy resin is 20 mol% to 80 mol% relative to a total content of the first structural unit and the second structural unit constituting the phenoxy resin.

Abstract: An insulated electric wire includes a linear conductor and an insulating film disposed to surround the periphery of the conductor. The insulating film includes a polyimide layer formed of a polyimide that has a molecular structure including a PMDA-ODA-type repeating unit A and a BPDA-ODA-type repeating unit B, the mole fraction [B×100/(A+B)] (% by mole) represented by the percentage of the number of moles of the repeating unit B to the total number of moles of the repeating unit A and the repeating unit B being 25% or more by mole and 95% or less by mole. The polyimide layer has a plurality of pores. The pores occupy 5% or more by volume and 80% or less by volume of the polyimide layer.