Acute phase rehabilitation is an important treatment for improving the functional outcome of patients after stroke. The present cohort study analyzed the feasibility and safety of acute phase rehabilitation using the hybrid assistive limb robot suit in 22 patients, 7 males and 15 females (mean age 66.6 ± 17.7 years). Neurological deterioration, mortality, or other accidents were recorded as adverse events. Baseline characteristics of each patient were recorded at the first hybrid assistive limb rehabilitation. Hybrid assistive limb rehabilitation was conducted for 12.1 ± 7.0 days with the patients in stable condition. Acute phase hybrid assistive limb rehabilitation was performed a total of 84 times with no adverse events recorded except for orthostatic hypotension. Good functional outcomes were obtained in 14 patients. Orthostatic hypotension was observed during the first hybrid assistive limb rehabilitation in four patients, and was significantly associated with intracerebral hemorrhage (p = 0.007) and lower Brunnstrom stage (p = 0.033). Acute phase rehabilitation using the hybrid assistive limb suit is feasible and safe. Patients with intracerebral hemorrhage and lower Brunnstrom stage should be carefully monitored for orthostatic hypotension.