A magnetic structural body contains core-shell structure particles each including a core section and a shell section covering the surface of the core section. The core section is made of an alloy containing a first metal and a second metal. The shell section is made of an alloy which contains the first metal and the second metal and which has a first metal-to-second metal content ratio different from that of the core section. The first metal is a magnetic metal and has a standard redox potential higher than that of the second metal. The neighboring core-shell structure particles are linearly linked to each other.