[Object] To newly develop a method whereby walnut can be simply, rapidly and accurately separated and distinguished from pecan nut.[Means for Resolution] Due to the increase in the number of patients with the walnut allergen and the increase of import of pecan nut which is an edible nut belonging to the family Juglandaceae, recently in Japan, the development of a method for detecting walnut and the nut in a discriminative manner is urgently needed. With attention focused on the chloroplast matK gene with the apparent gene sequence, we developed a PCR method for specifically detecting nuts of the family Juglandaceae and identified the matK sequence of pecan nut to establish a method for discriminating walnut and pecan nut from each other using restriction enzymes, for discriminating walnut and pecan nut from each other.