Meson-baryon nature of Lambda(1405) in chiral dynamics

We present the recent progress in the study on the origin of baryon resonances in chiral dynamics. It is shown that in the chiral coupled-channel approach, the form of the interaction cannot be specified due to the cutoff of the loop integral. To avoid this ambiguity, we propose a natural renormalization scheme, which affords a clue to the origin of the resonance, together with the phenomenological fitting to experimental data. We study the structure of the Lambda(1405) resonance in comparison with the N(1535).