  We define quantum phase in terms of inverses of annihilation and creation
operators. We show that like Susskind - Glogower phase operators, the measured
phase operators and the unitary phase operators can be defined in terms of the
inverse operators. However, for the unitary phase operator the Hilbert space
includes the negative energy states. The quantum phase in inverse operator
representation may find the applications in the field of quantum optics
particularly in the squeezed states.
