Abstract: In a Zeeman atomic absorption spectrophotometer, an atomic absorption signal in an atomization stage is observed. The length of time between an instant at which the signal initially attains a predetermined absorbance and an instant at which the signal attains the same predetermined absorbance for the last time during the atomization stage is measured. By utilizing this time measurement as an indication of concentration, the concentration of the sample can be measured at higher concentrations than the limit concentration in the analysis by a conventional apparatus of this kind.