There is provided a backlight device with which it is possible not only to prevent an assembly process from being complicated and the number of components from being increased, but also to connect a light source to a connector member satisfactorily and electrically. In this backlight device (20), a distance (W12) from the central axis (O1) of a cold cathode fluorescent lamp (23) to a connector terminal portion (240) is larger than a distance (W2) from the central axis of the cold cathode fluorescent lamp to an end portion of a contact portion (23d) of a cap portion (23a) in an F direction but is smaller than a distance (L2) from the central axis of the cold cathode fluorescent lamp to an end portion of the contact portion of the cap portion in an E direction.