An automatic analyzer, comprising: a cleaning bath that has a cleaning fluid outlet from which cleaning fluid is discharged for cleaning exterior of a probe, and a vacuum suction port into which the probe is inserted; a cleaning tank that stores the cleaning fluid; a vacuum tank; a vacuum pump configured to cause the vacuum tank to be placed under negative pressure with respect to atmospheric pressure; a vacuum bottle placed between the vacuum suction port and the vacuum tank; a pump configured to supply the cleaning fluid, stored in the cleaning tank, to the cleaning fluid outlet; a first solenoid valve; a second solenoid valve that is installed between the vacuum tank and the vacuum bottle; a third solenoid valve that is installed between the vacuum bottle and a drain; a first channel that connects between the vacuum suction port and the vacuum bottle; and a controller configured to control each mechanism of the automatic analyzer; characterized in that the first solenoid valve is installed between the pump and the cleaning fluid outlet; and a second channel and a third channel, wherein the third channel is between the first solenoid valve and the cleaning fluid outlet and has a branch point from which the second channel that is a bypass passage connects to the vacuum bottle, wherein the analyser is configured such that: by opening the first solenoid valve while the second and third solenoid valves (50b, 50c) are closed, the cleaning fluid is ejected from the cleaning fluid outlet, and by opening the second solenoid valve while the first and third solenoid valves (50a, 50c) are closed, the cleaning fluid (40w, 62w) flows into the vacuum bottle from the first channel and from the second channel. a cleaning bath that has a cleaning fluid outlet from which cleaning fluid is discharged for cleaning exterior of a probe, and a vacuum suction port into which the probe is inserted; a cleaning tank that stores the cleaning fluid; a vacuum tank; a vacuum pump configured to cause the vacuum tank to be placed under negative pressure with respect to atmospheric pressure; a vacuum bottle placed between the vacuum suction port and the vacuum tank; a pump configured to supply the cleaning fluid, stored in the cleaning tank, to the cleaning fluid outlet; a first solenoid valve; a second solenoid valve that is installed between the vacuum tank and the vacuum bottle; a third solenoid valve that is installed between the vacuum bottle and a drain; a first channel that connects between the vacuum suction port and the vacuum bottle; and a controller configured to control each mechanism of the automatic analyzer; characterized in that the first solenoid valve is installed between the pump and the cleaning fluid outlet; and a second channel and a third channel, wherein the third channel is between the first solenoid valve and the cleaning fluid outlet and has a branch point from which the second channel that is a bypass passage connects to the vacuum bottle, wherein the analyser is configured such that: by opening the first solenoid valve while the second and third solenoid valves (50b, 50c) are closed, the cleaning fluid is ejected from the cleaning fluid outlet, and by opening the second solenoid valve while the first and third solenoid valves (50a, 50c) are closed, the cleaning fluid (40w, 62w) flows into the vacuum bottle from the first channel and from the second channel. by opening the first solenoid valve while the second and third solenoid valves (50b, 50c) are closed, the cleaning fluid is ejected from the cleaning fluid outlet, and by opening the second solenoid valve while the first and third solenoid valves (50a, 50c) are closed, the cleaning fluid (40w, 62w) flows into the vacuum bottle from the first channel and from the second channel.