Ambiguity tolerance is an individual trait of preference for ambiguity that can be transformed by intervention. It is known that appreciation and discussion of art can improve ambiguity tolerance, but the effects of appreciation and discussion have not been separated, and there have been psychometric limitations. This study examined the effects of appreciation and creation on ambiguity tolerance using haiku, which are characterized by ambiguity and have been created by Japanese in their educational curriculum. The 152 participants in the zoom experiment answered the Multidimensional Attitude toward Ambiguity Scale at five time points: before and after haiku appreciation and creation, and one week later. The results showed that the absolutism, which is one factor of the attitude toward ambiguity, decreased after the appreciation and creation of haiku, and this effect persisted after one week, indicating that cognitive changes occurred through the appreciation and creation, which require various interpretations and choices.