PURPOSE: To prevent an electric shock by detecting the connecting condition only by the stable main position side whose potential is same with one side output end of a rectifier device, of output ends of the high-frequency converter device, in a high-frequency device made in a power source directly connecting type without using an insulating type transformer, and by stopping the output from the device when the connection is in a noncontact condition.

CONSTITUTION: When a discharge lamp 20 is connected normally, filaments 20b and 20a of the discharge lamp 20 are preheated by a high-frequency AC voltage, and the starting voltage is applied to the filaments so as to start the lighting of the discharge lamp 20. However, when the discharge lamp 20 is not connected normally, and only the filament 20a of the filaments 2Oa and 20b, for example, is connected to the output end (a) of a high-frequency converter device 4, but the 20b is not connected to the output end (b), a detecting means 31 to compose an output control device 30 detects the noncontact condition and outputs its detecting signal to a control circuit 32. As a result, the driving circuit 7 of the device 4 is controlled in the circuit 32, and the output from the device 4 is stopped or reduced. Consequently, even though a user is holding the discharge lamp 20, the current never flows through his body.