A powder for iron-based sintered-alloy valve sheets is provided which is excellent in compactibility and wearing resistance and is free from the precipitation of a carbide which may wear a mating member. A molten steel in which the content of carbon, which is regarded as an incidental impurity element, has been regulated to less than 0.1 mass% in order to avoid carbide precipitation and which contains 0.5-8.5 mass% silicon, 10-25 mass% nickel, 5-20 mass% molybdenum, and 5-20 mass% cobalt, with the remainder being iron and incidental impurities, is rapidly cooled by the gas atomization method,water atomization method, centrifugal atomization method, etc., which are conventional techniques, to thereby provide a powder of a supersaturated solid solution of the alloying elements. The solid solution consists mainly of austenite, which is effective in softening the powder. This powder has low hardness and hence has excellent moldability in compaction. On the other hand, the compact hardensthrough sintering and, hence, a valve sheet obtained therefrom as a final product has excellent wearing resistance. No carbide precipitation occurs, and there is hence no fear of causing a mating member to wear.