Provided is a capillary array unit configured to facilitate attaching/detaching operation. A capillary array unit includes a capillary, a load header provided at one end of the capillary, a capillary head provided at the other end of the capillary, a detection section provided at a portion of the capillary, and a holder holding the capillary. The holder includes a first holding section holding the capillary in a curved shape, a second holding section linearly holding the capillary, and a guide to move the second holding section in a predetermined direction.