  We investigate the finite size effect on masses of excited baryons in
quenched lattice QCD simulation. For this purpose, we perform numerical
simulations at three different lattice sizes, La\simeq 1.6, 2.2 and 3.2 fm. The
gauge configurations are generated with the single plaquette gauge action at
\beta=6/g^2=6.2, and the quark propagator are computed with the Wilson fermion
action. To access to two parity states of the nucleon and four different
spin-parity states of the \Delta baryon, the appropriate spin/parity projection
are carried out. We find that the spatial lattice size is required to be as
large as 3 fm to remove the finite size effect on excited baryons even in the
heavy quark region (M_\pi/M_\rho\simeq 0.82, 0.87), where that on the nucleon
is negligible. On our largest lattice (La\simeq 3.2 fm), all mass spectra of
the J^P=1/2^\pm nucleons and the J^P=1/2^\pm, 3/2^\pm \Delta baryons are
roughly consistent with experimental values after naive chiral extrapolation.
