Disclosed is a lactase preparation which does not undergo the deactivation of lactase even when the preparation is ingested prior to the ingestion of a lactose-containing food or beverage such as a milk product and therefore can decompose lactose stably and which can prevent the symptoms of lactose tolerance. Specifically disclosed is a lactase preparation comprising lactase and at least one component selected from trisodium citrate, potassium sodium tartrate, calcium carbonate, sodium carbonate and calcium hydrogen phosphate which acts as an antacid. The lactase preparation is characterized by being intended to be ingested prior to the ingestion of a lactose-containing food or beverage to decompose lactose. In the lactose preparation, the antacid is contained at such a content per unit dosage form that the pH value in the stomach can be increased to 4 or higher after the ingestion of the preparation.