PURPOSE: To obtain a fluorescent lamp for visible light hardening purpose with a high utility efficiency, by applying a phosphor mixing a specific strontium pyrophosphate phosphor and a specific strontium boro-phosphate phosphor over the inner surface of a glass tube.

CONSTITUTION: A mixture phosphor 1 is formed by mixing a strontium pyrophosphate phosphor A activated by a diatomic tin and strontium boro- phosphate phosphor B activated by a diatomic europium. The mixture phosphor 1 is applied over the inner surface of a glass tube 2, and a circular fluorescent lamp with electrodes 3 and 3' is made depending on the normal manufacture method. Therefore, compared with a haloid lamp used for a visible light hardening light source, the ratio of the radiation energy to the lamp input to the spectrum area 400W500nm which is the scope of the effective hardening wavelength of the visible light hardening resin is made larger. Consequently, the utility efficiency can be remarkably improved.