A resonance type flapping wing, which is suitable for an insect like Micro Air Vehicle, is presented. It utilizes the r esonance phenomenon of a two-degrees of freedom elastic system, that is, the wing is suppor ted by the spr ings for flapping and feathering motions, being oscillated, at the resonance frequency of the system, only by the torque in flapping motion. The amplitudes of flapping and feathering motions and the phase angle between them are controlled by changing the amount of the damping. Optimum design method is applied to determine the structural parameters of the wing, amount of the torque and damping. Using these optimum quantities thus determined, the arbitrary control of the flapping and feather ing motions becomes possible. The paper presents the theoretical bases of the concept, and the results of the numer ical simulation using a Navier-Stokes code, which takes into account the aeroelastic effects, are also presented to verify the concept.