In a magnetic field, the wave number of a pump laser light polarized along the field was fixed to the isolated Cs2D (1)Sigma(u)(+)(v=46, J=54)<--X (1)Sigma(g)(+)(v=0, J=55) line, and the excitation spectrum of the dissociated Cs(6p P-2(3/2)) atoms was measured by scanning the wave number of a probe laser light polarized perpendicular to the field. The population of each sublevel 6p P-2(3/2,mj) of the dissociated atoms was determined from the line intensities in the m(j)-resolved excitation spectrum. The unequal population between the 6p P-2(3/2,+\mj)\ and 6p P-2(3/2,-\mj)\ levels (atomic orientation) was observed and it was enhanced as the magnetic-field strength was increased. The atomic orientation is shown to be induced by the interference between the indirect predissociation, which occurs by a combination of the spin-orbit coupling of the D (1)Sigma(u)(+) state with the (2)(3)Pi(0u) state and the L-uncoupling and Zeeman interactions between the (2)(3)Pi(0u) and dissociative (2)(3)Sigma(u)(+) states, and the dissociation following a direct excitation to the (2)(3)Sigma(u)(+) state, which is allowed by spin-orbit coupling of the (2)(3)Sigma(u)(+) state with the B (1)Pi(u) state. It is demonstrated that the atomic orientation is produced by the photodissociation in the presence of an external magnetic field even when all degenerated molecular M=J,...,0,...,-J sublevels are excited by a light polarized linearly along the field.