Analysis system including a central control section for generally controlling the analysis that sends a command to perform a pre-injection operation, to an automatic sampler together with information designating a sample to be selected, such as an identification number, and simultaneously sends a command to perform an operation of measuring a dark current in a photodiode array (PDA) detector, to a multi-channel spectrophotometer. Thus, the automatic sampler performs the pre-injection operation, such as an operation of moving a needle to a position of a designated vial container to suck a sample, and the spectrophotometer performs the dark-current measurement operation during a time period of the pre-injection operation. After the sample is actually introduced into the column, in response to a command to perform a normal measurement operation, an operation of acquiring absorption data of an eluate from the column is started without performing the dark-current measurement operation.