A semiconductor apparatus includes a command decoding circuit and an enable signal generation circuit. The command decoding circuit generates a plurality of operation codes and a strobe pulse based on a command signal and a clock signal. The enable signal generation circuit generates a seed signal based on at least a part of an operation code, among the plurality of operation codes, and the strobe pulse, and generates an enable signal by shifting the seed signal. The enable signal generation circuit generates a plurality of guard keys, after the seed signal is generated, based on the plurality of operation codes and the strobe pulse, and prevents the generation of the enable signal when any one of the plurality of guard keys is disabled.