an electrolytic capacitor includes a capacitor element having a pair of lead terminals , a thermoplastic synthetic resin cases enclosing the element therein and a thermosetting synthetic resin coating formed on the thermoplastic synthetic resin cases with the lead terminals being extended outwardly . the thermosetting synthetic resin coating formed on the thermoplastic resin cases provides fine affinity with the lead terminals and encloses the capacitor element enclosed in the thermoplastic resin cases airtightly with the lead terminals being extended outwardly .