To eliminate a wasteful space inexpensively.

In this centering device in which a pair of pressing plates 13 which can approach/separate from each other are provided on the both sides of a conveying path 10 and an article W is centered at the center on the conveying path 10 by having both the pressing plates 13 close to each other and press the article W on the conveying path 10, an interlocking driving means 18 for connecting both the pressing plates 13 integrally to have them approach/ separate from each other and a plurality of free rollers 18a are arranged on an elevating table 16a provided below the conveying path 10, the article W on the conveying path 10 is pushed up by each of the free rollers 18a by elevating up the elevating table 16a, and both the pressing plates 13 are pressed onto the article W by the interlocking driving mechanism 17 so as to center the article W on the conveying path 10 at the center.