The kneading disc segment according to the present invention comprises plural disc sets each comprising two kneading discs and mounted on a kneading screw (3) which is for kneading a material while feeding the material to a downstream side. Disc sets each comprising a first kneading disc positioned on an upstream side and a second kneading disc, the second kneading disc being mounted continuously with and downstream of the first kneading disc so as to have a phase difference δ of an acute angle relative to the first kneading disc, are disposed continuously in the axial direction of the kneading screw. The first kneading discs in two continuous disc sets have a phase difference of 180°. With this construction, it is possible to attain a higher degree of kneading than in the conventional neutral kneading disc segment.