Synchronization between stacked spin Hall nano-oscillators (SHNO), attributed to the spin Hall effect and anisotropic magnetoresistance effect, was studied by numerical calculations. In order to obtain the synchronized state of the SHNOs, we considered the magneto-dipolar field, which was calculated in the rectangular prism. We revealed that the output power depended on the distance between the SHNOs, as the phase difference between the SHNOs depended on the coupling strength. For N = 3 (number of SHNOs), we investigated the phase difference by considering the influence of the coupling strength of all magnetic layers. Furthermore, we observed that the output power increased with the number of SHNOs in the synchronization system.