The invention provides a magnetic sheet including flat magnetic substance particles. The flat magnetic substance particles are formed by Fe-Si-Cr alloy. Oxygen membranes exist in surfaces of the flat magnetic substance particles. The average thickness of the oxygen membranes is 3.5-6.0 nm when the thickness of the oxygen membranes is defined as a distance from a topmost surface to a part having a half of the maximum oxygen intensity measured by a auger electron spectroscopy.