  We have designed and experimentally implemented a circuit of
inductively-coupled superconducting charge qubits, where a Josephson junction
is used as an inductance, and the coupling between the qubits is controlled by
an applied magnetic flux. Spectroscopic measurements on the circuit are in good
agreement with theoretical calculations. We observed anticrossings which
originate from the coupling between the qubit and the plasma mode of the
Josephson junction. Moreover, the size of the anticrossing depends on the
external magnetic flux, which demonstrates the controllability of the coupling.
