Abstract: An object of the invention is to provide a blow-molded foam which has homogeneous foamed cells in size, is light in weight, and is excellent in surface smoothness, and a process for producing the same. The invention is directed to a blow-molded foam 1 having a wall portion formed in such a manner that a thermoplastic resin containing a foaming agent mixed therewith is subjected to blow molding. Herein, the wall portion has a closed cell structure in which a plurality of foamed cells are contained. The wall portion has an expansion ratio of not less than 2.0 times. The wall portion has an outer face having a center-line average surface roughness Ra of less than 9.0 ?m. The foamed cell has a cell diameter having a standard deviation of less than 40 ?m in a thickness direction of the wall portion.