Objective : The purpose of this study was to investigate the effect of left visual stimuli for reducing the severity of unilateral neglect. Method : This research used a reversal design(ABAB) of single case study. The subject was a 60-year-old male patient who had left unilateral neglect. Remedial approach is more valuable method than compensatory approach in term of reducing the unilateral neglect. One of the method of remedial approach is controlled sensory stimulation. Result : I performed the line bisection test before and after the stimulation, and while doing that, put blinking lights to the patient from the left side. The average errors in the line bisection test decreased in B B', the intervention period, compared with A A'. The MVPT left response behavior score increased from 13 to 18. Conclusion : This shows that the light stimulation is effective in the reduction of unilateral neglect.