To improve image quality by obscuring density unevenness at a joint.

The liquid discharge device is provided with a control unit for forming an image on a medium by repeating a discharge operation to form a band with a plurality of dots arranged in a moving direction and a conveyance direction by discharging liquid from each nozzle while moving a nozzle string in the moving direction, and a conveyance operation to convey the medium in the conveyance direction in a conveyance amount shorter than the length of the nozzle string. The device includes a storage unit which stores a plurality of mask patterns for forming a joint of each band separately in a first area using a nozzle on one end side of the nozzle string and a second area using a nozzle on the other end side of the nozzle string. The first area and second area are different in shape.The boundary between the first area and second area has a boundary line at least oblique relative to the conveyance direction and moving direction. The control unit uses, in forming the image, different mask patterns of the plurality of mask patterns for a first joint and a second joint.