PURPOSE: To surely latch carriage by providing a latch beam having a cam-state curved surface which can contact with a latch pin to latch the latch pin and an actuator arm.

CONSTITUTION: When an error state is detected, an actuator arm 28 is moved toward its setting position, a first free side section 58 of a latch pin 36 contacts with a second free side section 62 of a curved surface 54 to bend a latch beam 34 in the downward direction. When a sufficient current is supplied to the arm 28, the side section 58 rides on a chip section 64 of a curved surface, the arm 28 is moved to its setting position, and a first latch section 56 of the pin 36 is positioned near a second latch section 60 of the curved surface 54. In order to release the arm 28, a sufficient current is required to supply to the arm 28 so that the actuator can drive by enabling that a side section 56 of the pin 36 rides on a side section 60 and jump over the chip section 64. Thereby, the arm 28 is released.