A reaction method that includes a reaction process of supplying and removing a liquid to and from a reaction site multiple times by using a pipette tip for drawing and ejecting a liquid attached to a pipette nozzle so as to allow two or more substances to cause a reaction, the method comprising: providing a heater for heating and keeping the pipette tip at a temperature in accordance with a preset temperature in a position that is close to an attaching position of the pipette tip ahead of a tip of the pipette nozzle; and attaching the pipette tip to the pipette nozzle and heating the pipette tip by a first preset temperature by the heater; the method being characterized by comprising: when a period of heating the pipette tip by the first preset temperature exceeds a preset period, switching an output of the heater from the first preset temperature to a second preset temperature that is lower than the first preset temperature so as to keep a temperature of the pipette tip by the second preset temperature; detecting a distal end position of the pipette tip in an axial direction of the pipette nozzle at or after the switching to the second preset temperature; and executing the reaction process while controlling the distal end position of the pipette tip by controlling movement of the pipette nozzle in the axial direction with reference to the detected distal end position, in which the temperature of the pipette tip is kept by the second preset temperature by the heater at least until operation of the pipette tip in the reaction process. providing a heater for heating and keeping the pipette tip at a temperature in accordance with a preset temperature in a position that is close to an attaching position of the pipette tip ahead of a tip of the pipette nozzle; and attaching the pipette tip to the pipette nozzle and heating the pipette tip by a first preset temperature by the heater; the method being characterized by comprising: when a period of heating the pipette tip by the first preset temperature exceeds a preset period, switching an output of the heater from the first preset temperature to a second preset temperature that is lower than the first preset temperature so as to keep a temperature of the pipette tip by the second preset temperature; detecting a distal end position of the pipette tip in an axial direction of the pipette nozzle at or after the switching to the second preset temperature; and executing the reaction process while controlling the distal end position of the pipette tip by controlling movement of the pipette nozzle in the axial direction with reference to the detected distal end position, in which the temperature of the pipette tip is kept by the second preset temperature by the heater at least until operation of the pipette tip in the reaction process. when a period of heating the pipette tip by the first preset temperature exceeds a preset period, switching an output of the heater from the first preset temperature to a second preset temperature that is lower than the first preset temperature so as to keep a temperature of the pipette tip by the second preset temperature; detecting a distal end position of the pipette tip in an axial direction of the pipette nozzle at or after the switching to the second preset temperature; and executing the reaction process while controlling the distal end position of the pipette tip by controlling movement of the pipette nozzle in the axial direction with reference to the detected distal end position, in which the temperature of the pipette tip is kept by the second preset temperature by the heater at least until operation of the pipette tip in the reaction process.