An apparatus and method for calculating an internal state for artificial emotions are disclosed, of which the method comprises multiplying an input value obtained from a sensor with a first personality set in accordance with at least one low rank element contained in at least one high rank element of a NEO PI-R (Revised NEO Personality Inventory); calculating a personality factor value in a Five-Factor Model of the personality by adding the results of the multiplication; and calculating the internal state by multiplying the personality factor value with a second personality.