The invention relates to an iron-based soft magnetic powder for a dust core, wherein a film comprising Fe and Co, a phosphoric acid-based chemical conversion film and a silicone resin film are formed in this order on the surface of an iron-based soft magnetic powder, and to a dust core obtained by molding the iron-based soft magnetic powder for a dust core. The invention also relates to an iron-based soft magnetic powder for a dust core formed by coating the surface of an iron-based soft magnetic powder with an insulating film, wherein the powder has a particle diameter of from 45 μm to 180 μm, the insulating film is composed of two layers in which a lower layer composed of a phosphoric acid-based chemical conversion film and an upper layer composed of a silicone resin film, and each of the films has a thickness of from 100 nm to 280 nm, and to a dust core obtained by molding the iron-based soft magnetic powder for a dust core.