An automatic analyzer configured to perform qualitative and quantitative analysis of a liquid obtained by reaction of a sample and a reagent, the automatic analyzer comprising: a reaction disk that includes a plurality of reaction vessels for reaction of the sample with the reagent; a sample dispensing probe configured to dispense the sample to the reaction vessels on the reaction disk; a sample dispensing probe cleaning tank configured to clean an outer periphery of the sample dispensing probe after the sample is dispensed; a reagent dispensing probe configured to dispense the reagent to the reaction vessels on the reaction disk; a reagent dispensing probe cleaning tank configured to clean an outer periphery of the reagent dispensing probe after the reagent is dispensed; a cleaning mechanism configured to clean the reaction vessels after measurement is completed; a water supply mechanism configured to supply cleaning water to the sample dispensing probe, the sample dispensing probe cleaning tank, the reagent dispensing probe, the reagent dispensing probe cleaning tank and the cleaning mechanism; characterized by a control unit configured to, when the sample is not analyzed by the automatic analyzer and is in a standby state capable of accepting the measurement of the sample, execute a quasi-stop mode in which supply of the cleaning water supplied by the water supply mechanism is not completely stopped and a supply amount is controlled to be smaller than a supply amount during the measurement of the sample; and a quasi-stop mode execution selection screen for selecting whether to execute the quasi-stop mode, wherein the quasi-stop mode is a mode in which, based on a quasi-stop mode condition table in which setting conditions of a stop condition and a start condition of the cleaning water are stored, supply of the cleaning water to at least one of the sample dispensing probe, the sample dispensing probe cleaning tank, the reagent dispensing probe, the reagent dispensing probe cleaning tank and the cleaning mechanism is stopped, and supply of the cleaning water to one or more of the above is continued. a reaction disk that includes a plurality of reaction vessels for reaction of the sample with the reagent; a sample dispensing probe configured to dispense the sample to the reaction vessels on the reaction disk; a sample dispensing probe cleaning tank configured to clean an outer periphery of the sample dispensing probe after the sample is dispensed; a reagent dispensing probe configured to dispense the reagent to the reaction vessels on the reaction disk; a reagent dispensing probe cleaning tank configured to clean an outer periphery of the reagent dispensing probe after the reagent is dispensed; a cleaning mechanism configured to clean the reaction vessels after measurement is completed; a water supply mechanism configured to supply cleaning water to the sample dispensing probe, the sample dispensing probe cleaning tank, the reagent dispensing probe, the reagent dispensing probe cleaning tank and the cleaning mechanism; characterized by a control unit configured to, when the sample is not analyzed by the automatic analyzer and is in a standby state capable of accepting the measurement of the sample, execute a quasi-stop mode in which supply of the cleaning water supplied by the water supply mechanism is not completely stopped and a supply amount is controlled to be smaller than a supply amount during the measurement of the sample; and a quasi-stop mode execution selection screen for selecting whether to execute the quasi-stop mode, wherein the quasi-stop mode is a mode in which, based on a quasi-stop mode condition table in which setting conditions of a stop condition and a start condition of the cleaning water are stored, supply of the cleaning water to at least one of the sample dispensing probe, the sample dispensing probe cleaning tank, the reagent dispensing probe, the reagent dispensing probe cleaning tank and the cleaning mechanism is stopped, and supply of the cleaning water to one or more of the above is continued.