Abstract: A pseudo-LSI device for emulating a single electronic circuit using a plurality of programmable logic elements mounted on a common circuit board, providing a pseudo-operation unit comprising a plurality of programmable gate arrays constituting a pseudo-LSI when having circuit data written thereto, a nonvolatile memory unit for storing the circuit data to be downloaded from outside, a transfer unit for transferring the circuit data stored in the nonvolatile memory unit to the pseudo-operation unit, and a power supply unit, said four units being provided in the form of an assembly, which can be used in developing LSIs and to debugging systems.