A computation partitioning method is arranged to automatically convert a sequential source program for a single processor into a partitioned computation for a distributed memory machines containing plural processors. The method is executed to analyze a syntax of a source program described in a high-level language containing at least one loop having plural assignment statements, each assignment having an array, distribute the array element in the source program and at least one loop and allocate the partitioned parts of the array element to the processors. For each processor, then, the method is further executed to derive a loop iteration set corresponding to an array element distributed to the processor for plural assignment statements in at least one loop and generate a new array having the sum set of the derived loop iteration set as its array elements. By using the new generated array index as the loop iteration set of the assignment statements in at least one loop, the partitioned computation to be executed by each processor is generated.