PROBLEM TO BE SOLVED: To provide a method for effectively improving the filterability of plant raw material sap, and to provide the plant raw material sap and a beverage.SOLUTION: A method includes filtering, at a temperature exceeding 78°C, a first plant raw material sap prepared using a plant raw material, whose content of barley malt not rid of hull is less than 50 wt.%, to produce a second plant raw material sap, whose &bgr;-glucan content is less than 0.1 wt.%, for the use to produce the beverage. The method may further include producing a beverage using the second plant raw material sap.