The reproducibility and reliability of research are fundamental tenets in science, and in animal psychology. In the field of animal psychology, researchers have used a number of different species in various tasks and settings, such that considerations of the reproducibility are necessary compared with human research. Furthermore, using the appropriate statistical analysis and improving experimental design, a concrete theoretical background underlying each research question seems only to be important for improving the reproducibility between experiments in which the same species were used, but also in the situation where different species have been used. Because it is sometimes difficult to standardize the tasks and settings among investigations in animal psychology, theoretical consideration should help improve the reproducibility of research, as well as the validity of the interpretation of results obtained. Such efforts would also contribute to reduce the unnecessary use of animals from the perspective of animal welfare.