To provide a slow start circuit suited for extending the service life of a lamp by suppressing a rush current when lighting the lamp, or for smoothly starting a motor or the like without a shock.

A reactance (coil) 5 is connected between one pair of bridges b and d of a bridge type rectifier 4 and the secondary side of a transformer 2 is connected between the other pair of bridges a and c through, for example, a load 10 such as a lamp or motor. When a switch 3 is turned on, a current which does not rise immediately but gradually reaches a maximum value (MAX) and which then returns to its normal value is caused to flow through the load 10 by the action of the reactance 5, as shown in Figure 1 (B). The maximum current value is not as high as it is with conventional techniques, so that a starting rush current can be kept low when the switch 3 is turned on.