A semiconductor memory device having a semiconductor substrate includes a plurality of reference cells 4 and a plurality of bit lines 10. The reference cells 4 are formed in a region near the centerline of a predetermined region of the semiconductor substrate which is perpendicular to the bit lines 10. The bit lines 10 form pairs each composed of two adjacent bit lines. Two bit lines 10 in each pair have a first parallel state and a second parallel state in which positions of the two bit lines are reversed from the first parallel state. Each pair of bit lines 10 has at least one cross section 11 where one of the pair of bit lines 10 crosses the other, to switch between the first parallel state and the second parallel state. The cross section 11 is provided in the predetermined region of the semiconductor substrate such that the length of a bit line 10 in the first parallel state is equal to the length of the bit line 10 in the second parallel state. The semiconductor memory device is reduced in size.