Purpose The purpose of this study was to investigate changes in standing posture using tilt-table stepping robot rehabilitation, in the context of posture specificity of patients with rigid bilateral cerebral palsy. Methods In the case of an 18-year-old spastic diplegia cerebral palsy patient, Erigo an upright robot rehabilitation exercise-and Bobath-concept general physical therapy were performed for 30 minutes, three times per week, for four weeks from August 16 to September 4, 2018. Coordination of balance and body movement in static and dynamic sitting postures was evaluated with the Korean Trunk Impairment Scale (K-TIS), and Postural Assessment Scale for Stroke-Trunk Control (PASS) and 10-meter walking test and GAITRite were used to evaluate walking ability. The static pressure of the foot was measured using a BIORescue. To assess postural changes before and after intervention, changes in head position were measured. Results Scores on the Korean TIS remained unchanged, at 14/23 both before and after the intervention; scores on the PASS also remained unchanged, at 30/36 both before and after the intervention. For static foot pressure, front foot pressure decreased by 7.3%, from 55.4% before the intervention to 48.1% after the intervention, and back foot pressure increased by 7.3%, from 44.6% to 51.9%. In the 10-meter walking test, the time taken to walk 10 meters decreased by 4 seconds, from 14 seconds to 10 seconds, and measurements by the GAITRite system showed that gait velocity decreased by 19.1 seconds, from 52.5 seconds to 33.4 seconds, and single foot support increased by 0.19, from 0.09 to 0.28. Conclusion After 4 weeks of standing-up robot training and general physical therapy training, the 10-meter walking test and footprint showed improved results. This seems to be the result of improved standing and dynamic balancing ability of the patient with spastic diplegic cerebral palsy.