1. A loop conversion method in an information processing system having a processor and a memory, comprising: a step performed by said processor, of generating an instruction for accessing data formed of a plurality of source array elements which are arrayed in a plurality of dimensions; a step performed by said processor of recognizing an accessing process of loop nest within codes containing said instruction; a step performed by said processor, of transposing and copying the source array elements between at least two positions on different dimensions in said plurality of dimensions, to a one dimensional destination array including at least a continuous array in said memory; and a step performed by said processor, of converting an access of said instruction to said source array elements to an access to said destination array.