A semiconductor device having a stacked structure including through-silicon-vias (TSVs) and a method of testing the semiconductor device. The semiconductor device includes a first semiconductor layer, one or more second semiconductor layers stacked on the first semiconductor layer, and a plurality of input through-silicon-vias (TSVs) to transmit signals from a plurality of input pads, respectively. In a test mode, a test signal from the plurality of input pads is transmitted through at least two test paths, and the test signal transmitted through each of the test paths is output as a test result with respect to each of the plurality of input TSVs through an output pad.