PURPOSE: To obtain a haloborophosphate fluorescent substance of an alkaline earth metal activated with a bivalent Eu of high luminous efficiency, by calcining a raw material mixture, washing the calcined raw material, and baking the washed material in an oxidizing atmosphere.

CONSTITUTION: A raw material mixture is calcined usually at 900W1,200°C in a reducing atmosphere, washed with distilled water, and baked preferably at 380W 600°C, optimally at 400W550°C, in an oxidizing atmosphere to give the aimed haloborophosphate fluorescent substance of an alkaline earth metal, activated with a bivalent Eu, and expressed by the formula (M and M' are Sr, Ca or Ba; X is Cl, F or Br; 2.5≤x≤3.0; 0.50≤y≤1.5; 0.10≤a≤0.50; 0.01≤b≤0.50, 0.001≤ p≤0.20). SrHPO4, BaCO3, Eu2O3, H3BO3, CaCl2, etc. may be used as the raw material mixture.