The semihard magnetic alloy of the present invention consists essentially of, by weight, 17 to 45 % chromium, 3 to 14 % cobalt, 0.2 to 5 % silicon and balance substantially iron, preferably 23 to 35 % chromium, 6 to 12 % cobalt, 0.3 to 3 % silicon and balance substantially iron and has a residual magnetic flux density of 7,000 Gauss or more and a coersive force of 100 to 600 Oersted. Said alloy is produced by solution treating an alloy having the above indicated composition at a temperature of 650.degree.C. to 1,300.degree.C., preferably 850.degree.C. to 1,085.degree.C., and then either maintaining the solution-treated alloy at a temperature of not higher than 650.degree.C. for a given period of time and repeatedly aging said alloy in multi-stage at gradually lowered temperatures, or cooling the solution-treated alloy continuously from a temperature of not higher than 700.degree.C. down to at least 550.degree.C. at a rate of not higher than 50.degree.C. per hour.