The purpose of the present invention is to improve the recovery of small size ores by reducing the amount of loss of small size ores in a washing/separation step. This nickel ore washing device (100) washes the ore slurry (S) of nickel oxide ores and is characterized in that: the nickel ore washing device is provided with an introduction unit (102) for introducing the ore slurry, an ore separation/recovery screen (104) for separating ores with a grain size of not larger than a predetermined grain size from the ore slurry supplied by the introduction unit, a washing water supply unit (106) for supplying washing water (W) to the ore slurry supplied to the ore separation/recovery screen, and a recovery unit (108) for recovering small size ores OS contained in the ore slurry, the recovery unit being disposed on the opposite side of the washing water supply unit with the ore separation/recovery screen therebetween; the introduction unit supplies the ore slurry from one end side to the other end side of the ore sep
