A clock switching circuit which is fed with clock signals corresponding to respective elements of a redundant system and outputs a clock signal corresponding to the system in operation while relaxing the phase fluctuation in response to a change in the system construction and a node device which is provided with the clock switching circuit. Useless accumulation of phase error is prevented with neither a drastic change in the construction nor a degradation of performance. Therefore, the clock switching circuit is constructed such that the phase of a synchronous clock signal synchronized with a clock signal corresponding to an element used antecedently is stepwise varied alternately in opposite directions each time the element being used is updated.
