A memory system comprises a controller capable of controlling a memory operation, and memory connectors capable of mounting memory modules therein, both of which are provided on a system board. Each of the memory modules has a plurality of memory chips connected to module data wirings and module power wirings respectively. The module data wirings of each memory module are connected in series form through series paths lying within the connectors. Each individual module data wirings do not constitute branch wirings to system data wirings on the system board. Thus, such signal reflection as caused by branching from the data wirings on the system board is not developed. Since the power is supplied in parallel from the system board through parallel paths lying within the connectors, the supply of the power is stabilized.