To provide a rind puffing inhibitor of citrus fruits without containing a micronutrient as an essential component.

The rind puffing inhibitor of the citrus fruits comprises potassium secondary phosphate as an active ingredient and is subjected to foliar spraying as an aqueous solution at 100-500 times dilution ratio of the potassium secondary phosphate. When sprayed in the summer and autumn season, the inhibitor is effective for inhibiting the rind puffing of the citrus fruits. Since the active (essential) ingredient is only the potassium secondary phosphate and the micronutrient such as boron which requires to avoid the excess is not the essential ingredient, there is no need of application considering the amount of the micronutrient fertilized (contained in a fertilizer). The inhibitor is a rind puffing inhibitor readily usable by a farmer.