To surely and effectively perform separating operation of a lot of mixture by simple operation.

In this countercurrent multistage liquid-liquid extractor, an agitating vessel 2 equipped with an agitating means for agitating a light liquid and a heavy liquid for liquid-liquid extraction is provided with a light liquid separating and sending part 3 for separating the heavy liquid and sending the light liquid, a heavy liquid separating and sending part 4 for separating the light liquid and sending the heavy liquid, a light liquid introducing part 5 into which the light liquid is introduced, and a heavy liquid introducing part 6 into which the heavy liquid is introduced to form a liquid-liquid extraction unit 1. The light liquid separating and sending parts 3 and the light liquid introducing parts 5 in the plural liquid-liquid extraction units 1 are connected in order, and also the heavy liquid separating and sending parts 4 and the heavy liquid introducing parts 6 are connected in order.