Within an extended chiral constituent quark model, three- and five-quark structure of the $S_{01}$ resonance $Lambda(1405)$ is investigated. Helicity amplitudes for the electromagnetic decays ($Lambda(1405) to Lambda(1116)gamma$, $Sigma(1194)gamma$), and transition amplitudes for strong decays ($Lambda(1405)toSigma(1194)pi$, $ K^{-}p$) are drived, as well as the relevant decay widths. The experimental value for the strong decay width, $Gamma_{Lambda(1405)to (Sigma pi)^circ}=50pm 2$ MeV, is well reproduced with about 50% of five-quark admixture in the $Lambda(1405)$. Important effects due to the configuration mixings among $Lambda^{2}_{1}P_{A}$, $Lambda^{2}_{8}P_{M}$ and $Lambda^{4}_{8}P_{M}$ are found. In addition, transitions between the three- and five-quark components in the baryons turn out to be significant in both radiative and strong decays of the $Lambda(1405)$ resonance.
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