An ink switching cam (40) is rotated interlockingly with forward/reverse rotation of a head driving motor at all times to swing a cassette support member (20). Accordingly, ink belts can be switched with a simple construction without using a solenoid or the like. By setting a movable area of the ink switching cam (40) to be within one rotation, the operations of a print head (10) and the ink switching cam (40) which are interlocked with the forward/reverse rotation of the head driving motor can be simply associated with each other.