This paper reports a novel triple mass resonator (TMR) consisting of two tuning fork type outer masses and an inner mass, which could increase capacity to tune the quality factor (Q-factor). Q-factor related to the anchor loss (QAnchor) could be controlled by electrostatic softening on springs connected to the inner mass, while the resonant frequency of anti-phase mode was almost constant. In contrast, when the DC bias was applied to the outer mass, the resonance frequency could be tuned same as conventional electrostatic softening. The experimental results showed the Q-factor decrease as large as 64.8% could be obtained by the DC bias of 15 V at the inner electrode, while the frequency change was as small as 278 ppm. On the other hand, when the bias was applied to the outer mass, frequency drop as high as 4429 ppm and Q-factor change as small as 9.8% could be obtained. By the proposed method, both Q-factor and resonance frequency could be controlled by the DC biases applied to the inner and outer masses, respectively.