In a printer, an accommodating portion accommodates printing agent supplied from a first cartridge. A print execution device prints with the printing agent supplied from the accommodating portion. A processor acquires first information concerning a residual quantity of the printing agent remaining in the first cartridge. The processor acquires second information concerning a preparation of a second cartridge to be replaced with the first cartridge. If the residual quantity is below a reference quantity and if the second information is acquired, the processor allows the print execution device to perform printing under a cartridge removed state where the first cartridge is removed from the mount portion. If the residual quantity is larger than or equal to the reference quantity or if the second information is not acquired, the processor prohibits the print execution device from printing under the cartridge removed state.