A semiconductor integrated circuit includes a test input/output port including test pads; an internal input interface configured to generate an internal clock, an internal address, an internal command, internal data and temporary storage data in response to external signals through the test input/output port; and an error detection block configured to determine whether the internal data and the temporary storage data are the same, and output a result through one test pad of the port. The internal input interface includes a data input/output block which generates the internal data and the data input/output block includes a temporary storage part which stores the internal data as the temporary storage data, a data output part which receives the temporary storage data, and a data input part which receives an output of the data output part and outputs it as the internal data.