This paper examines the reason why the finite form of adjectives can sometimes alternate with the adjective + naru when it appears in the consequence clause of the conditionals as shown in "Homerareruto, ureshii/ureshiku-naru (I would be pleased if I am praised)." It is argued that the alternation becomes possible only when the adjective expresses either "the instantaneous feeling of experiencers" or "the property of events themselves". When the adjective is interpreted as "the instantaneous feeling", the meaning becomes synonymous to the change of psychological state that is usually expressed by the adjective + naru. When the adjective + naru is interpreted as "the property of event", the meaning of adjective + naru also approaches to the static property that is usually expressed by the adjective. The alternation phenomena indicate the continuity between the dynamic event and the static property mediated by psychological expressions.