A printing material supply system includes a printing device and a cartridge. The printing device has a cartridge mounting structure. The cartridge is removably attached to the cartridge mounting structure. The cartridge mounting structure has a device-side terminal, a lever, a first device-side locking element and a second device-side locking element. The first device-side locking element is configured as part of the lever to lock the cartridge at a position on a positive Z-axis side and on a positive X-axis side of the device-side terminal. The second device-side locking element is configured to lock the cartridge at a position on a positive Z-axis side and on a negative X-axis side of the printing material supply tube.