A power supply unit for an aerosol inhaler, which causes an aerosol generated from an aerosol source to pass through a flavor source, includes: a power supply dischargeable to a first load configured to heat the aerosol source and dischargeable to a second load configured to heat the flavor source; a notification unit; a processing device; a circuit board; and a conductive portion configured to electrically connect the second load and the circuit board. The processing device is configured to detect adhesion of a liquid to the second load or entry of the liquid into the conductive portion. When the adhesion or the entry is detected, the processing device executes at least one of a notification action that causes the notification unit to execute a notification and a first fail-safe action including prevention of discharging from the power supply to the second load.