To provide a classifier requiring remarkably less amount of fresh water used for washing classification and recovering particles serving as product sand from crushed sand raw material containing fine sand component.

The classifier is composed of: a settling tank 1 to which crushed sand raw material from a raw material charging port 1a is charged; a carrying out means 2 carrying out from the settling tank 1 the particles settled on the bottom among the crushed sand raw material charged to the settling tank 1; a washing and dewatering means 3 sprinkling fresh water as washing water supplied from a fresh water supply means 4 from above through a washing water discharge port 3b, to a vibration dewatering screen 3a discharging particles carried out from the carrying out means 2 while applying vibration to the particle, and recovering the washing water containing fine sand dropping from the vibration dewatering screen 3a by a reflux trough 3c and returning to the settling tank 1; and an overflow water treating means 6 having a reflux means 6b refluxing part of overflow water containing fine sand recovered by an overflow water recovering means 5 and overflowing from the settling tank 1 from a drain tank 6a storing the overflow water, and a draining means 6c draining surplus overflow water remaining in the drain tank 6a.