A liquid crystal display device has a fluorescent lamp and a driving circuit as a back light. A closed container, a discharge gas sealed in the closed container, first discharge electrodes, and second discharge electrodes are included in the fluorescent lamp. The driving circuit repeats a first step of causing electric discharge in first discharge areas by applying a voltage having a negative polarity to the first discharge electrodes and a voltage having a positive polarity to the second discharge electrodes, and a second step of causing electric discharge in second discharge areas which are different from the first discharge areas by applying a voltage having a positive polarity to the first discharge electrodes and a voltage having a negative polarity to the second discharge electrodes.