Disclosed is a sandwich type steel sheet having low specific gravity and high stiffness which may be applied to an exterior plate of a vehicle and the like, which require excellent strength, dent resistance and the like. Further, a method of manufacturing the sandwich type steel sheet having a low specific gravity and high stiffness is also disclosed. Particularly, the sandwich type steel sheet includes an upper steel sheet positioned at an upper portion; a lower steel sheet positioned at a lower portion; a polymer layer containing an amount of about 50 to 60 wt % of a polyamide 6 resin, an amount of about 25 to 45 wt % of a polyolefin resin, based on a total weight of the polymer layer. Therefore, the thickness of the steel sheets may be reduced by about 20% from the conventional steep sheet, and strength, dent resistance and the like may be enhanced. In addition, clunking, a slight noise of opening and closing doors, and the like, which are caused by a thin steel sheet and discomfort of a passenger by heavy rainy sound may be eliminated.