A box-packing system having a first conveyor, a first robot that applies suction, holds, and transports a package, and a control device. The package includes soft packaging material, and is conveyed by the first conveyor. The control device operates the first robot to move the package to a box-packing preparation area. The first robot has a suction part applying suction the package from above, an arm that moves the suction part in a horizontal direction and a vertical direction, and a servomotor. The servomotor drives the arm so that the suction part can apply suction to the package at a predetermined vertical location. An acquisition part of the control device acquires thickness information of the package. The determination part determines the predetermined height location based the thickness information. The command generation part drives the servomotor in response to the predetermined height location determined by the determination part.