PROBLEM TO BE SOLVED: To provide a bitterness masking agent which masks, for gastric absorption, safely, inexpensively and easily, bitterness of an edible material including a drug food-and-drink, even when the edible food-and-drink is a fine powder or a whole fruit, by using a traditional food material, in a long-term antifungal/denaturalization-preventive way, even in an ordinary-temperature hydrated state of the edible food-and-drink, without degradation or denaturalization of the contained ingredients or production of industrial waste.SOLUTION: A bitterness masking agent for masking of the bitter ingredient of olive contains ethanol-containing sake lees or calcium hydroxide as an effective ingredient having action of masking the bitter ingredient of olive and is used effectively by simple mixing. A bitterness masking method uses the bitterness masking agent in masking the bitter ingredient of olive. The bitterness masking method may includes additionally a step of a treatment with carbonates. The bitterne
