To provide a method for spinning a sea-island type multi-island conjugated fiber with which spinning stability is excellent without joining of mutual island components and variation of island fineness is slight without increasing the size of a spinneret and without reducing the throughput of discharge holes by increasing the islands and to provide a spinneret device.

The method for spinning the sea-island type conjugated fiber comprises preparing a plurality of core-sheath conjugated streams on the upstream side, gathering the streams in a primary funnel-shaped part, joining the gathered streams so as to be surrounded with a plurality of other core-sheath conjugated streams on the downstream side, further gathering the joined streams in a secondary funnel-shaped part on the downstream side and spinning the resultant gathered streams from each discharge hole. In the method, when the throughput of one core-sheath conjugated stream prepared on the upstream side per unit time is Q1; the number of the core-sheath conjugated streams prepared on the upstream side is n1; the throughput of one core-sheath conjugated stream prepared on the downstream side per unit time is Q2; the number of the core-sheath conjugated streams prepared on the downstream side is n2; the inside diameter of the outlet part of a through-hole for leading the core-sheath conjugated streams gathered in the primary funnel-shaped part to the downstream side is d1; and the inside diameter of the secondary funnel-shaped part at a position to provide the same height as that of the outlet part of the through-hole is d2, the relationship among them satisfies formula 0.5≤{n1Q1(d22-d12)}/(n2Q2d12)≤3.0.