A component mounting machine, comprising: a mounting base (60, 78) provided in a component mounting machine main body and movable at least in the horizontal direction; a mounting/demounting tool (50, 76), detachably mounted on the mounting base (60, 78) and movable in the up-down direction while holding a component; a tool moving mechanism configured to move the mounting/demounting tool (50, 76) in the up-down direction; a mounting base moving mechanism configured to move the mounting base (60, 78) at least in the horizontal direction; a control device (36, 73) configured to perform a seating improvement process to improve the engagement between the mounting base (60, 78) and the mounting/demounting tool (50, 76) such that the positional relationship between them is stable by applying a force in a predetermined direction, including at least the horizontal direction and preferably the up-down direction, to the mounting base (60, 78) on which the mounting/demounting tool (50, 76) is mounted, after the mounting/demounting tool (50, 76) is mounted on the mounting base (60, 78) but before the mounting/demounting tool (50, 76) holds the component, by a moving operation different from a moving operation for holding the component on the mounting/demounting tool (50, 76) in the mounting base moving mechanism, wherein the control device (36, 73) is configured to repeatedly execute the other moving operation, which is the seating improvement process, in the mounting base moving mechanism multiple times after the mounting/demounting tool (50, 76) is mounted on the mounting base (60, 78) but before the mounting/demounting tool (50, 76) holds the component. a mounting base (60, 78) provided in a component mounting machine main body and movable at least in the horizontal direction; a mounting/demounting tool (50, 76), detachably mounted on the mounting base (60, 78) and movable in the up-down direction while holding a component; a tool moving mechanism configured to move the mounting/demounting tool (50, 76) in the up-down direction; a mounting base moving mechanism configured to move the mounting base (60, 78) at least in the horizontal direction; a control device (36, 73) configured to perform a seating improvement process to improve the engagement between the mounting base (60, 78) and the mounting/demounting tool (50, 76) such that the positional relationship between them is stable by applying a force in a predetermined direction, including at least the horizontal direction and preferably the up-down direction, to the mounting base (60, 78) on which the mounting/demounting tool (50, 76) is mounted, after the mounting/demounting tool (50, 76) is mounted on the mounting base (60, 78) but before the mounting/demounting tool (50, 76) holds the component, by a moving operation different from a moving operation for holding the component on the mounting/demounting tool (50, 76) in the mounting base moving mechanism, wherein the control device (36, 73) is configured to repeatedly execute the other moving operation, which is the seating improvement process, in the mounting base moving mechanism multiple times after the mounting/demounting tool (50, 76) is mounted on the mounting base (60, 78) but before the mounting/demounting tool (50, 76) holds the component.