A cartridge mounting mechanism includes a chamber that accommodates therein a cartridge introduced through a cartridge inlet formed as an opening directed upward, a biasing mechanism that biases the cartridge set in the chamber in an upward direction corresponding to a removal direction of the cartridge, and a holding mechanism configured to be engaged with the cartridge so as to restrict, against a biasing force of the biasing mechanism, the cartridge from moving in the removal direction when the cartridge is set in the chamber, and disengaged from the cartridge to release the cartridge from the restriction against the biasing force, upon being subjected to an external operating force.