A rodent repellent device of random working frequency is disclosed, which comprises: an application-specific integrated circuit (ASIC); a deterring module, electrically connected to the ASIC, capable of emitting a wave emission selected from the group consisting of an ultrasonic wave, a seismic wave and a sound, being used for repelling rodents; and a power source, electrically connected to the ASIC, for providing power to the ASIC and the deterring module. Wherein the ASIC further comprises: an internal precision oscillator; a center processing unit (CPU); a wake-up module, being employed as an activation means for enabling the rodent repellent device to have randomized lasting time of wave emission and randomized intermission between two consecutive wave emissions; a read-only memory (ROM), for storing a program controlling the randomization of each intermission between two consecutive wave emissions and the lasting time of each wave emissions; and a random-access memory (RAM).