In a superconducting random access memory according to this invention, drive lines such as a word line and a bit line, and a sense line for accessing a memory cell array are each divided into a plurality of blocks and an in-block signal propagation circuit having a level-logic drive circuit and sense circuit each with high load drive capability is used for signal propagation in each of the blocks. Further, for long-distance signal propagation between the blocks, superconducting passive transmission lines formed by single flux quantum (SFQ) devices and capable of high-speed operation are used. As a result, the high-speed operation as a whole is enabled. It is possible to additionally use splitters or confluence buffers and latch circuits and, further, a binary tree structure may be adopted.