Z-scan measurements using a tunable picosecond laser were performed on one-dimensional metal complexes to investigate the nonlinear refraction and nonlinear absorption. Nonlinear refractive indices were measured to be positive/negative at wavelengths shorter/longer than the excitonic peak. Strong saturable absorption was noticeable on resonance, although small induced absorption was observed at the absorption tail. Optical nonlinearities were enhanced due to the resonance effect to give the maximum values of -8.1x10(-7) esu and -6.7x10(-7) esu for Re chi((3)) and Im chi((3)), respectively.