An insulated electrical wire is provided. The insulated electrical wire includes a conductor and an insulating film including pores. The insulating film at least includes a first insulating layer. The first insulating layer includes a first center region, a first inner side region, and a first outer side region. The first center region is a center region in the first insulating layer in a thickness direction and is formed of an insulating material and first pores that are the pores. The first pores are derived from a liquid thermally decomposable polymer. The first inner side region and the first outer side region are formed not to include the first pores.