PROBLEM TO BE SOLVED : To provide dried Polygonum tinctorium Lour. leaves containing enzyme in the state of high enzymatic activity, to provide methods for producing the dried Polygonum tinctorium Lour. leaves efficiently, to provide dried Polygonum tinctorium Lour. leaves suitable for hair dyeing, coloring, as a precipitation or a pigment, and to provide a Polygonum tinctorium Lour. precipitation or a Polygonum tinctorium Lour. pigment for medicines, cosmetics, soap, coloring, or functional foods. SOLUTION : Provided is a method in which the amount of functional materials in dried Polygonum tinctorium Lour. leaves is held high or increased, as compared with normal low-temperature dried or microwave reduced pressure dried Polygonum tinctorium Lour. leaves, by controlling enzymes in raw Polygonum tinctorium Lour. leaves by microwave irradiation, in a microwave drying or aging-drying method of Polygonum tinctorium Lour. leaves. By the control of enzymatic activity in raw Polygonum tinctorium Lour. leaves, the enzymatic activity in raw Polygonum tinctorium Lour. leaves is controlled, or activated, and promoted. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT