A process for producing sodium hydrogencarbonate crystal particles having a low caking property, which entails subjecting sodium hydrogencarbonate crystal particles having an average particle size of from 50 to 500 μm based on the mass to heat treatment at a temperature of from 70 to 95° C. by a heating gas having a carbon dioxide gas concentration of at most the concentration calculated by the formula: Carbon dioxide gas concentration=0.071×e(0.1×T)×R(−0.0005×T−0.9574), where T (° C.) is the temperature of sodium hydrogencarbonate crystals, and R (%) is the relative humidity around the crystals at the temperature of the crystals, provided that the upper limit of the carbon dioxide gas concentration is 100 vol % to form anhydrous sodium carbonate on the surface of the sodium hydrogencarbonate crystal particles with a content of anhydrous sodium carbonate of from 0.03 to 0.4 mass % in the sodium hydrogencarbonate crystals.