Disclosed is a method for changing emotion of a software robot (sobot) in a sobot terminal. The sobot terminal includes a short-term memory unit and a long-term memory unit. When an emotional change occurs during the operation of the short-term memory unit, the sobot terminal stores a short-term reference emotion value of the corresponding emotion in the long-term reference memory. When the operation time of the long-term memory unit elapses, the sobot terminal resets the long-term reference emotion value using the short-term reference emotion values stored in the long-term memory unit. The sobot terminal can change the emotion of the sobot more naturally through the above process.