The impurity Green's function G(f) in the local non-Fermi liquid state is evaluated by means of the continuous-time quantum Monte Carlo method extended to the multichannel Anderson model. For N = M (where N and M are numbers of spin components and channels, respectively), G(f) is expressed as -ImG(f)(omega + i0) = c - b vertical bar omega vertical bar(1/2), and the zero-frequency value c depends only on N (= M). A corresponding impurity self-energy at low frequencies is composed of two parts: a resonance term related to c, and a non-Fermi liquid term proportional to vertical bar omega vertical bar(1/2). The characteristic energy scale is discussed in terms of the non-Fermi liquid term in the self-energy.