This study experimentally investigates the flow fields around rigid and chordwise-flexible wings, performing a rectilinear translational motion starting from rest. A rigid wing and two flexible wings with an intermediate degree of flexibility and a high degree of flexibility are considered in this study. Phase-locked planar particle image velocimetry measurements are performed at the 75% span position of the wings at the Reynolds number of 7360. The results reveal the presence of a coherent LEV and a series of vortices shedding from the trailing edge of the wing in the acceleration phase. At the late stages of the constant-speed phase, the LEV moves away from the wing surface and bursts into smaller flow structures in the case of the rigid wing and the wing with an intermediate degree of flexibility. In the case of the wing with a high degree of flexibility, a smaller geometric angle of attack is attained due to a larger chordwise deformation of the wing, resulting in a coherent LEV positioned close to the wing surface throughout the motion. A stable LEV and the associated low-pressure region and the increased size of the horizontal surface area may elevate the resultant lift force.