A semiconductor device with laser-programmable fuses for repairing a memory defect found after production, in which guard rings and fuse patterns are designed to take up less chip space. The semiconductor device has a fuse pattern running parallel to the longitudinal axis of a rectangular guard ring, and patterns branching from the fuse pattern and drawn out of the guard ring in the direction perpendicular to that axis. The semiconductor device also has a plurality of memory cell arrays, each coupled to an I/O port for receiving and sending memory signals. One of those arrays is reserved as a redundant memory cell array for repair purposes. The device further has switch circuits for switching the connection between the I/O ports and memory cell arrays, selecting either default memory cell arrays of the I/O ports or their adjacent memory cell arrays, including the redundant memory cell array.