  The quantum damped harmonic oscillator is described by the master equation
with usual Lindblad form. The equation has been solved completely by us in
arXiv : 0710.2724 [quant-ph]. To construct the general solution a few facts of
representation theory based on the Lie algebra $su(1,1)$ were used.
  In this paper we treat a general model described by a master equation with
generalized Lindblad form. Then we examine the algebraic structure related to
some Lie algebras and construct the interesting approximate solution.
