An automatic analyzer having an operation mode setting unit adapted to let an operator select an operation mode from: a normal mode for carrying out analysis preparation operation items which are set in advance and which include replacement of system reagents and disposal of reaction containers, and a time-saving mode for carrying out fewer analysis preparation operation items than in the normal mode, an analyzer condition monitoring unit adapted to monitor the condition of the analyzer between the completion of a starting processing of the analyzer and the start of an analysis preparation operation for preparing for an analysis operation and between the completion of an analysis-ending operation and the start of an analysis preparation operation for preparing for the next analysis operation, the condition of the analyzer including at least one of: presence or absence of a malfunction during starting processing of the automatic analyzer (S110), presence or absence of a malfunction during the analysis operation (S110), presence or absence of access by the operator to an analysis unit between the completion of the analysis operation and the start of the next analysis preparation operation (S120), presence or absence of maintenance carried out between the completion of the analysis operation and the start of the next analysis preparation operation (S140), and presence or absence of a change of a reagent used for the analysis operation (S130), and an analysis preparation operation item determining unit adapted to determine (S100, S110, S120, S130, S140, S141) analysis preparation operation items to be carried out as the analysis preparation operation, based on the operation mode set at the operation mode setting unit and on the monitoring result of the analyzer condition monitoring unit, wheein if the operation mode is not the time-saving mode, all said analysis preparation operation items are carried out (S151), and if the operation mode is the time saving mode: all said analysis preparation operation items are carried out (S151) when the last analysis operation or starting processing did not end properly (S110) or the operator has accessed the analysis unit (S120), whereas otherwise: all said analysis preparation operation items except for the disposal of the reaction containers are carried out (S153) when the system reagent bottles have been changed (S130), and when the system reagent bottles have not been changed (S130), all said analysis preparation operation items except for the replacement of the system reagents and the disposal of the reaction containers are carried out (S152) when maintenance was not carried out (S140) and system reagents were not replaced by water (S141) but all said analysis preparation operation items except for the disposal of the reaction containers are carried out (S153) when maintenance was carried out (S140) and the system reagents were replaced by water (S141). a normal mode for carrying out analysis preparation operation items which are set in advance and which include replacement of system reagents and disposal of reaction containers, and a time-saving mode for carrying out fewer analysis preparation operation items than in the normal mode, <EOS>