Electronic device capable of providing a restraining installation sequence for different modules and case module thereof

A case module that is capable of providing a restraining installation sequence for a first electronic module and a second electronic module, includes a cage and a restraining component. The first electronic module can move relative to the cage to a first installation position along a first direction. The second electronic module can move relative to the cage to a second installation position along a second direction perpendicular to the first direction. When the first electronic module moves relative to the cage toward the first installation position along the first direction, the restraining component is driven to move relative to the cage toward a restraining position along the first direction. The second electronic module can be stopped by the restraining component when the restraining component is located at the restraining position.