A fluorescent lamp capable of fully securing a portion for containing a mercury amalgam pellet and reliably preventing the mercury amalgam pellet from moving toward the inside a discharge tube, and a method for manufacturing the fluorescent lamp. The fluorescent lamp includes a glass tube having a fluorescent substance layer on the inner surface, a sealed portion formed at an end of the glass tube, a slender glass tube having an inner space that is in communication with the inside of the glass tube and is not in communication with the outside of the glass tube, and a mercury amalgam pellet contained in the slender glass tube. The slender glass tube has a small-diameter part with an inner diameter smaller than the diameter of the mercury amalgam pellet and a large-diameter part with an inner diameter larger than the diameter of the mercury amalgam pellet. The slender glass tube is welded to the glass tube so that the small-diameter part is placed in the sealed portion and the large-diameter part is placed further away from the glass tube than the smaller-diameter part.