A capacitor type welding device comprising: a charging circuit configured to convert an input AC electric power to a DC electric power and output the DC electric power, and including a hybrid bridge full wave rectifier circuit, which has thyristors (2A, 2B, 2C) and rectifier diodes (2a, 2b, 2c) connected in a bridge structure, or a thyristor full wave rectifier circuit, which has thyristors connected in a bridge structure; a welding transformer having a primary winding and a secondary winding; a welding capacitor configured to be charged by a charging current which flows in a charging path from the charging circuit, the charging path including at least the primary winding or an inductor connected in series to the primary winding and provided between the charging circuit and the primary winding; a bypass switching element connected in parallel across output terminals of the charging circuit, and having a forward-blocking function to cause a backflow current, which flows due to a magnetic energy stored in an inductance of the primary winding or the inductor of the charging path, to bypass the charging circuit; characterized in comprising a discharge switching element configured to discharge the charged electric charge of the welding capacitor through the welding transformer to perform welding when the DC electric power is not supplied to the welding capacitor from the charging circuit; and a control circuit configured to bring the bypass switching element into a conduction state when the backflow current flows, and to bring the discharge switching element into the conduction state after the bypass switching element enters a non-conduction state and recovers the forward-blocking function. a charging circuit configured to convert an input AC electric power to a DC electric power and output the DC electric power, and including a hybrid bridge full wave rectifier circuit, which has thyristors (2A, 2B, 2C) and rectifier diodes (2a, 2b, 2c) connected in a bridge structure, or a thyristor full wave rectifier circuit, which has thyristors connected in a bridge structure; a welding transformer having a primary winding and a secondary winding; a welding capacitor configured to be charged by a charging current which flows in a charging path from the charging circuit, the charging path including at least the primary winding or an inductor connected in series to the primary winding and provided between the charging circuit and the primary winding; a bypass switching element connected in parallel across output terminals of the charging circuit, and having a forward-blocking function to cause a backflow current, which flows due to a magnetic energy stored in an inductance of the primary winding or the inductor of the charging path, to bypass the charging circuit; characterized in comprising a discharge switching element configured to discharge the charged electric charge of the welding capacitor through the welding transformer to perform welding when the DC electric power is not supplied to the welding capacitor from the charging circuit; and a control circuit configured to bring the bypass switching element into a conduction state when the backflow current flows, and to bring the discharge switching element into the conduction state after the bypass switching element enters a non-conduction state and recovers the forward-blocking function.