Abstract: A modular device for administering a fluid medicament fixable to the skin of a user includes a reservoir module with a reservoir defining a first axis, a first connecting structure and a first electrical contact arrangement; and a pump module with a piston rod defining a second axis, a second connecting structure arranged around the piston rod, and a second electrical contact arrangement. The first and second connecting structures are plugged together and the first axis and the second axes lie on a common axis forming a rotational axis. The pump module is rotated relative to the reservoir module about this rotational axis to electrically connect the first and second electrical contact arrangements. The first contact arrangement is displaced radially farther from the first axis than the first connecting structure, and the second electrical contact arrangement is displaced radially farther from the second axis than the second connecting structure.