Unilateral spatial neglect (USN) is a higher cognitive dysfunction that can occur after a stroke. It is defined as an impairment in finding, reporting, reacting to, and directing to stimuli presented opposite to the damaged side of the brain. So far, we have developed an immersive virtual reality system that releases the attention biased to the non-neglected side and guides it to the neglected side to improve the symptoms of neglect. However, it improved neglect symptoms evaluated using a paper-and-pencil test on a desk (i.e., Behavioral Inattention Test), and it did not improve neglect in daily life evaluated using a standardized evaluation tool [i.e., Catherine Bergego Scale (CBS)], which is a rating index of neglect in actual daily life. Therefore, establishing a method for improving neglect in daily life is necessary. This study was designed to develop a platform for improving neglect in daily life as an initial investigation of rehabilitation methods for patients with USN. To improve neglect, the following three elements were derived from previous studies that should be included in rehabilitation: object search by moving around, reproduction of the complexity of daily life, and own body movement in the neglected side with visual confirmation. The patient moves around the room and visually explores and touches the objects presented in the mixed reality (MR) space. Using this system, we conducted a validity test on a patient with USN. The results showed that the patient improved from moderate to mild neglect in the CBS. Thus, the applicability of proposed MR system was suggested in terms of improving neglect in patients with USN in daily life environment.