An insulating tape having a mica layer, a reinforcing layer having a filler and a fiber reinforcing material laminated on the mica layer, and a cellulose derivative layer laminated on the reinforcing layer is provided. One or more hydroxyl groups in the glucose units of the cellulose derivative are substituted with a functional group such as —CH2CH2OH or —(CH2CH2O)pH (where p is any repeating number up to 50). The weight per unit area of the mica ranges from 100 g/m2 to 200 g/m2. The filler has a maximum particle size of 100 μm or smaller and a weight per unit area ranging from 10 g/m2 to 50 g/m2. The insulating tape is useful to form a stator coil insulating layer with high thermal conductivity, with no outflow of a filler to the exterior during production of the stator coil, and with enhanced bonding strength.