This study uses the effect of flexibility on the propulsive efficiency of swimmers that consist of superparamagnetic particles and which are subjected to an oscillating field to control the movement in a low Reynolds number environment. To achieve nonreciprocal motion for a flexible swimmer using a simple and stable structure, two types of artificial flexible swimmers are constructed using self-assembled beads without links and the flexibility and the bending rigidity are investigated under various frequencies. At a low frequency, both the head and the tail oscillate almost synchronously with the field, which leads to a nearly rigid and reciprocal oscillation. The phase angle trajectory for the head significantly leads the tail at a higher frequency of oscillation, which results in a prominent flexible structure and propulsion generation. Furthermore, the flexibility initially increases linearly with the frequency and then reaches the highest value at a specific frequency. The instantaneous velocity of the swimmer almost linearly increases with its flexibility. The most effective oscillating frequency to manipulate the locomotion for the magnetic microbeads swimmer would be at f=7-10 Hz, which resists the amplitude and enhances the flexibility of the microswimmer. Finally, a flexible swimmer associated with a moderate high oscillating amplitude is a favorable configuration for propulsion generation.