Disclosed are a method for measuring βG comprising the steps of bringing a sample into contact with a βG-binding protein 1 and a βG-binding protein 2, each comprising an amino acid sequence which is identical or substantially identical to an amino acid sequence shown in any one of SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, or SEQ ID NO:20, and having the β-glucan binding activity, to form a complex of the βG-binding protein 1, βG in the sample and the βG-binding protein 2, measuring quantity of the complex, and determining βG concentration in the sample based on the quantity of the complex; a reagent and a kit for use in said method; a novel βG-binding protein; a nucleic acid molecule encoding the βG-binding protein; and a method for producing the aforementioned βG-binding protein.