A component insertion assembly device equipped with a chuck device for grasping a component and inserting downward facing protrusions of the component into holes in a target item; wherein the chuck device comprises a clamping section for performing a clamp movement/clamp release movement to the downward facing protrusions of the component, and a pusher section for pushing the downward facing protrusions of the component into the holes in the target item; wherein the component insertion assembly device further comprises a moving mechanism for moving the chuck device in the horizontal direction and up/down direction; and a control device for controlling the push movement of the pusher section and the clamp movement/clamp release movement of the clamping section as well as controlling the moving mechanism to control the movement of the chuck device in the horizontal direction and up/down direction; and wherein the control device, controls in order i) the clamping section to perform the clamp movement to the downward facing protrusions of the component, ii) the moving mechanism such that the lower end of the protrusions are inserted into holes in the target item, iii) the clamping section to perform the clamp release movement to the downward facing protrusions of the component, iv) the moving mechanism such that the chuck device is moved in a direction away from the component, which is a direction perpendicular to the clamp release movement direction of the clamping section, to a position that the clamping section does not interfere with the component while the clamping section is raised, and the pusher section is above the component, v) the pusher section to perform a downwards push movement so as to insert the downward facing protrusions of the component further into the holes in the target item, and vi) the moving mechanism such that the chuck device is raised and the clamping section and pusher section are raised to a position higher than the component; and wherein the opening amount during the clamp release movement of the clamping section is set so that interference does not occur with an adjacent already mounted component; the component insertion assembly device being characterized by the chuck device comprising two air cylinder sections (57, 58) for moving the clamping section and the pusher section respectively; and a shared air supply entrance for supplying air having negative/atmospheric pressure to a pressure chamber of the air cylinder section for clamping so as to perform the clamp movement/clamp release movement respectively and for supplying air having positive pressure to a pressure chamber of the air cylinder section for pushing so as to perform the downwards push movement; and wherein the control device further controls the two air cylinder sections (57, 58). i) the clamping section to perform the clamp movement to the downward facing protrusions of the component, ii) the moving mechanism such that the lower end of the protrusions are inserted into holes in the target item, iii) the clamping section to perform the clamp release movement to the downward facing protrusions of the component, iv) the moving mechanism such that the chuck device is moved in a direction away from the component, which is a direction perpendicular to the clamp release movement direction of the clamping section, to a position that the clamping section does not interfere with the component while the clamping section is raised, and the pusher section is above the component, v) the pusher section to perform a downwards push movement so as to insert the downward facing protrusions of the component further into the holes in the target item, and vi) the moving mechanism such that the chuck device is raised and the clamping section and pusher section are raised to a position higher than the component; and