Disclosed are a washing machine and a detergent device thereof. Same are intended to solve the problem of existing detergent boxes being unable to fully dissolve detergent comprising washing powder in water. For this aim, the detergent device comprises a detergent box (1) and a water storage module (2), wherein the detergent box (1) is provided with a water outlet, and an impeller (13) is arranged at the water outlet; the water storage module (2) comprises water inlet cavities (21, 22), a water outlet cavity (23) and a separation plate (24) arranged between the water inlet cavities and the water outlet cavity, and through holes (241, 242) are provided on the separation plate (24) to communicate the water inlet cavities (21, 22) with the water outlet cavity (23). When the detergent box (1) is inserted into the water outlet cavity (23), the through hole (242) is at the projecting position, on the separation plate (24), of the impeller (13), such that water falling from the through hole (242) and a detergent sol
