To tackle the jittering of a robot arm-tip, a novel method of the jittering mitigation is proposed. The key idea is to transmit the jittering to vibration of a mass block nested inside the jittering-mitigator. This method only requires the frequency of the jittering at the arm-tip. To verify the practicability of the method, a practical robot was applied through simulations and physical experiments. The jittering mitigator device can be directly attached to or detached from the arm-tip. The jittering at the arm-tip was first measured through experiments using accelerometers connected to the vibration and noise testing system. Then, the dominant frequency was identified through fast Fourier transform analysis. The theoretical parameters of the jittering mitigator were calculated accordingly. A model was established to simulate the jitter reduction effect of the mitigator. The results revealed a 68% reduction in the average amplitude of the jittering vibration at the arm-tip, which is corroborated by the experiment results. The proposed method could be applicable to all types of robot because it only requires computing the frequency of jitter.