A flaky powder for high frequency application is provided, wherein the flaky powder contains 1.5 to 3.0 mass % C, 10 to 20 mass % Cr, 0.03 to 0.30 mass % N, and the balance being Fe and incidental impurities, and has an average particle diameter of 200 μm or less, an average thickness of 5 μm or less, an average aspect ratio of 5 or more, a saturation magnetization of more than 1.0 T, and a frequency (FR) of 200 MHz or more at which tan δ reaches 0.1. Based on the flaky powder, a novel magnetic flaky metal powder having a saturation magnetization exceeding 1.0 T and exhibiting a high FR of 200 MHz or more, and magnetic sheets including the magnetic flaky metal powder are provided.