New regenerated cellulose fibers are prepared from solution (chemical cellulose con tents, 3, 4.5, 6, and 9 wt%) using N-methylmorpholine-N-oxide (NMMO)/water (87/13 wt%) as a solvent by dry-wet spinning at a winding speed of 20-100 m/min. The chemical cellulose (97% α-cellulose content, 918 DPw, 98% JIS whiteness) used for this study is prepared from ascidian tunicates by a modified pulping process described in our previous work. The effects of cellulose content and spinning speed on the structure and mechanical properties of fibers are investigated. As the cellulose content increases, the birefringence, crystallinity, and initial tensile modulus of the fibers increase significantly. While the tenacity of the fibers increases with increasing cellulose content up to 6 wt%, there is a great decrease in the tenacity at 9 wt%. That decrease is due to fiber defects. Mechanical properties increase with increasing winding speed. The regenerated cellulosic fibers prepared in this study have a higher ratio of wet strength to dry strength compared to regenerated cellulose fibers produced all over the world.