A fluorescent lamp can be configured to prevent a decrease in luminescent efficiency when located in a high temperature room. The fluorescent lamp can include a couple of stems each including an emitter electrode located opposite to each other at each end of a tube, a filler gas located in the tube, a damping material and a coolest portion connected to the tube via the stem and the damping material. The coolest portion can be configured with a first material that has a higher thermal conductivity than the conductivity of both the tube and the stems. The damping material can be configured with both the first material and a second material that has a lower conductivity than the conductivity of the first material. A content ratio of first material vs. second material can change along a length of the damping material. Thus, the coolest portion can maintain a favorable temperature and the fluorescent lamp can maintain a favorable luminescent efficiency even when in a sealed casing.