ProblemsDevelopment of a process of producing inexpensive and safe hexose and compositions of the same.Means for ResolutionA process of producing a sugar composition comprising a definite amount of an target hexose, comprising treating a starting liquid sugar material comprising a starting sugar material hexose or a mixture comprising hexose in a system in the presence of one or more types selected from the group consisting of basic ion exchange resins, alkalis and calcium salts to initiate an isomerization reaction as an equilibrium reaction to transform the starting sugar material hexose to the target hexose to prepare a sugar mixture comprising a definite amount of the target hexose and having a sugar constitution different from that of the starting sugar material, and hexose compositions containing D-allose and D-psicose and the use of the hexose compositions.