A method for reducing the cost of stack scanning in garbage collection (GC) includes, in the GC of the first-generation heap area, registering, in a nursery object reference list prepared for each thread, one or more addresses, within each stack, which each refer to a nursery object, and updating a scanning unnecessary area starting pointer such that the addresses listed in the nursery object reference list are included in the area from the bottom of the stack to the address pointed to by the scanning unnecessary area starting pointer. The method further includes, in the next GC of the first-generation heap area, for the area from the bottom of the stack to the address pointed to by the scanning unnecessary area starting pointer, performing the GC processing on the addresses included in the nursery object reference list.