Generator coordinate method (GCM) combined with particle number and triaxial angular momentum (spin) projections is applied to single j-shell model with the monopole-pairing interaction (MPI) and the quadrupole-quadrupole interaction (QQI). The GCM calculation yields excellent results, e.g. the GCM with the QQI reproduces exact energy spectra of all the excited states for 4-hole (also particle) systems in the j = 112 152 and 192 shells; and the GCM with the MPI plus QQI, which requires simultaneously the particle number projection, reproduces exact energy spectra for the 6-hole (also particle) systems except for the spin I = 1 state in the j = 132 shell. it turns out that components of triaxial deformation contribute much to reproduce correct physical states, so that the triaxial spin projection is essential in the present GCM.