§** †† The Japan Aerospace Exploration Agency (JAXA) is now developing a 20N-class thruster valve for spacecraft propulsion systems. We intend to develop this valve with the high reliability, and a robust and durable design. The suspended armature type was chosen for the base design of the new 20N valve based on the results of a trade-off study. Experiments and analysis were performed for the critical parts and manufacturing process. The results enabled us to manufacture a prototype model with single type 20N thruster valves. Good results were obtained in functional tests. We will now proceed to the next phase and complete the detailed design for series redundancy and prepare for the qualification test. Nomenclature a σ = stress amplitude B σ = tensile yield stress m σ = mean stress max σ = maximum stress min σ = minimum stress w σ = Endurance limit when completely reversed