An endoscope reprocessor comprising: a treatment tank configured to allow an endoscope to be disposed inside; a connector including an opening inside the treatment tank and being connected to the endoscope; and a first conduit extending from the connector toward a ground side relative to the treatment tank; an on-off valve disposed in the first conduit; a leak tester including a gas pump and a pressure sensor disposed at a position that is closer to the ground than the treatment tank, the leak tester being configured to test a leak from the endoscope; characterized in that the endoscope reprocessor further comprises: a second conduit including one end portion that is connected to a part of the first conduit between the on-off valve and the connector, and another end portion that is connected to the leak tester to communicate the part with the leak tester, the second conduit having a flow passage cross-sectional area that is smaller than a flow passage cross-sectional area of the first conduit, or having an inner portion including a flexed portion flexed in a direction away from the ground, so that a conduit resistance of a conduit body of the second conduit is higher than a conduit resistance of a conduit body of the first conduit, the conduit resistance being a resistance determined by the conduit shape and properties, wherein the leak tester is configured to pressurize an inside of the endoscope by the gas pump and measure a pressure inside the endoscope by the pressure sensor through the first conduit, the second conduit, and the connector in a state where the on-off valve is closed. a treatment tank configured to allow an endoscope to be disposed inside; a connector including an opening inside the treatment tank and being connected to the endoscope; and a first conduit extending from the connector toward a ground side relative to the treatment tank; an on-off valve disposed in the first conduit; a leak tester including a gas pump and a pressure sensor disposed at a position that is closer to the ground than the treatment tank, the leak tester being configured to test a leak from the endoscope; characterized in that the endoscope reprocessor further comprises: a second conduit including one end portion that is connected to a part of the first conduit between the on-off valve and the connector, and another end portion that is connected to the leak tester to communicate the part with the leak tester, the second conduit having a flow passage cross-sectional area that is smaller than a flow passage cross-sectional area of the first conduit, or having an inner portion including a flexed portion flexed in a direction away from the ground, so that a conduit resistance of a conduit body of the second conduit is higher than a conduit resistance of a conduit body of the first conduit, the conduit resistance being a resistance determined by the conduit shape and properties, wherein the leak tester is configured to pressurize an inside of the endoscope by the gas pump and measure a pressure inside the endoscope by the pressure sensor through the first conduit, the second conduit, and the connector in a state where the on-off valve is closed. a second conduit including one end portion that is connected to a part of the first conduit between the on-off valve and the connector, and another end portion that is connected to the leak tester to communicate the part with the leak tester, the second conduit having a flow passage cross-sectional area that is smaller than a flow passage cross-sectional area of the first conduit, or having an inner portion including a flexed portion flexed in a direction away from the ground, so that a conduit resistance of a conduit body of the second conduit is higher than a conduit resistance of a conduit body of the first conduit, the conduit resistance being a resistance determined by the conduit shape and properties, wherein the leak tester is configured to pressurize an inside of the endoscope by the gas pump and measure a pressure inside the endoscope by the pressure sensor through the first conduit, the second conduit, and the connector in a state where the on-off valve is closed.