A printer includes, a printing portion configured to print on a print medium, a ribbon supply shaft configured to hold an ink ribbon to be supplied to the printing portion, a ribbon roll up shaft configured to roll up the ink ribbon used in the printing portion, a partition member provided swingably, the partition member partitioning the ink ribbon and the print medium; and a ribbon supply shaft lock mechanism configured to regulate rotation of the ribbon supply shaft, wherein the ribbon supply shaft lock mechanism is switched between a lock state where the rotation of the ribbon supply shaft is regulated and a non-lock state where the rotation of the ribbon supply shaft is permitted in conjunction with swing actions of the partition member.