The present invention have objects to provide an option of non-reducing saccharide by providing a novel non-reducing saccharide composed of glucose as constituents and to provide a novel enzyme forming the non-reducing saccharide, a method and process for producing the same, a DNA encoding the enzyme, a recombinant DNA and transformant comprising the DNA, a composition comprising the non-reducing saccharide, and uses thereof. The present invention solves the above objects by providing an isocyclomaltooligosaccharide(s) having a structure represented by General Formula 1, a novel isocyclomaltooligosaccharide-forming enzyme, a method and process for producing the same, a DNA encoding the enzyme, a recombinant DNA and transformant comprising the DNA, a composition comprising the isocyclomaltooligosaccharide(s) or a saccharide composition comprising the same, and uses thereof. Cyclo{.fwdarw.6)-[.alpha.-D-Glcp-(1.fwdarw.4)].sub.n-.alpha.-D-Glcp-(1.fw- darw.} General Formula 1 (In General Formula 1, "n" means a number of 4 or 5).