PURPOSE: To surely make a self-excited oscillation-type Reuer circuit rise in a short time.

CONSTITUTION: A Reuer circuit is provided with one pair of transistors Q1, Q2 connected in series with respective windings NP1, Np2 on opposite sides of the intermediate tap of a primary winding of a transformer T. A DC input Vin is applied between a series circuit of Np1 and Q1 and a series circuit of windings Np2 and Q2. A voltage which is induced at feedback windings Nf1, Nf2 of the transformer T is positively fed back to the respective transistors Q1, Q2 via an oscillating capacitor C2. Thereby, the transistors Q1, Q2 are turned on and off alternately. Different DC biases are applied to the transistors Q1, Q2 by using resistances R1, R2. Thereby, when the DC input Vin is applied, the transistor Q1 is first turned on, and it is possible to prevent a state that the transistors Q1, Q2 are turned on in a halfway state.