PURPOSE: The purpose of this study was to identify the effects on the cognitive function, Activities of Daily Living (ADL), mood, social behaviors, and problematic behaviors of robot pet-assisted program for elderly people with dementia. METHODS: This study was a nonequivalent control group pretest-posttest design. The participants were 32 elders with dementia. Seventeen were assigned to the experimental group and 15 to the control group. The intervention was conducted twice a week for 6 weeks. RESULTS: 1) After the program, cognitive function, ADL, and social behaviors did not show significant differences. 2) After the program, mood of experimental group was significantly better than that of the control group. 3) After the program, problematic behaviors of the experimental group were significantly more diminished than those of control group. 4) As a result of analyzing the response, robot pet-assisted program was effective such as inducing a positive emotional state and increasing communication and interaction. CONCLUSION: The robot pet-assisted program was effective in changing the mood and diminishing problematic behaviors and had positive effects such as increasing communication and interaction for elders with dementia. Therefore, this program should be considered as a positive program for physical and emotional support for elders with dementia.