Abstract: In the flash device disclosed, a control circuit for controlling the charging operation of a main capacitor is provided with a switching means for forming a path for charging the main capacitor; and a signal forming circuit which produces opening and closing signals for control over the switching means. The switching means is alternately opened and closed by the opening and closing signals to intermittently charge the main capacitor. When the main capacitor is completely charged, the signal forming means produces only the closing signal causing the switching means to cyclically block the charging path. Thus, even if the switching means is subject to operation by a noise which further charges the main capacitor after the charging operation has been completed, this further charging can be immediately stopped. Thus, the main capacitor does not become overcharged.