A spinneret assembly for sheath-and-core type composite fibres capable of corresponding to various spinning conditions, with a small degree of eccentricity of core component and a small quality of variance and provided densely with a large number of spinning holes is provided, which assembly comprises a cap having two spinning liquid reservoirs for core component liquid and sheath component liquid partitioned by a partition wall; a filter; a first distribution plate having introducing holes for alternately distributing the liquids into subsequent distribution grooves; a second distribution plate having on its back surface, straight distribution grooves prepared by cutting in parallel and also having on its flat front surface, perforated liquid pressure control holes for leading the distributed liquids to a subsequent spinneret plate; a spinneret plate having on its flat back surface, perforated spinning holes having the common axes to the core component pressure control holes of the second distribution plate; and a spacer for forming a narrow clearance between the second distribution plate and the spinneret plate; the respective core component pressure control holes being located at a point of intersection of two diagonals of a square or ectangle formed by adjacent four sheath component pressure control holes.