A lamp device includes: a lamp unit mounted in a lamp housing; and a circuit unit disposed in the lamp housing for activating the lamp unit to emit light when receiving an external voltage through opposite connecting ports mounted on the lamp housing. The lamp unit includes two cold cathode fluorescent lamps (CCFLs) connected in series. Each CCFL includes a lamp tube that has a first tube segment connected to a first electrode portion and extending in a first direction, a second tube segment connected to a second electrode portion and extending in a second direction transverse to the first direction, and a curved third tube segment interconnecting the first and second tube segments. For each CCFL, a ratio of a length of the lamp tube in the second direction to a length of the same in the first direction is less than 25%.