The invention relates to a jigger, in particular to a jigger capable of collecting undersize material by a machine. The jigger comprises a pulsating system, an upper body, a lower body and an oversize material discharging channel, a current common jigger pulsating system is adopted by the pulsating system of the jigger, a current common upper body of a jigger bellows system is adopted by the upper body of the jigger, the lower body of the jigger is formed by the machine device which is mounted on the bottom of the lower body and specially used for collecting and excluding the undersize material and a lower body shell, and guiding plates specially used for material collecting and a discharging port specially used for discharging are mounted on the lower body shell. According to the jigger, after the undersize material of an existing jigger is collected by the machine device, the height of the lower body of the jigger is greatly reduced, the structure is simple, and the jigger is particularly applicable to enterprises of factories and mines with limited installation space such as coal mine downhole and the interior of a die block.