The present invention provides a synchronous semiconductor device suitable for improving the efficiency of application of electrical stresses to the device, an inspection system and an inspection method thereof in order to efficiently carrying out a burn-in stress test. A command latch circuit having an access command input will output a low-level pulse in synchronism with an external clock. The pulse will pass through a NAND gate of test mode sequence circuit and a common NAND gate to output a low-level internal precharge signal, which will reset a word line activating signal from the control circuit. Simultaneously, an internal precharge signal passing through the NAND gate will be delayed by an internal timer a predetermined period of time to output through the NAND gate a low-level internal active signal, which will set a word line activating signal from the control circuit.