  On the basis of the canonical quantization procedure, in which we need the
indefinite metric Hilbert space, we formulate field diagonal representation for
the scalar Lee-Wick model. Euclidean path integral for the model is then
constructed in terms of the eigenvector of field operators. Taking the quantum
mechanical Lee-Wick model as an example, we demonstrate how to formulate path
integrals for such systems in detail. We show that, despite the use of
indefinite metric representation, integration contours for ghost degrees can be
taken along the real axis.
