There are increasing opportunities to engage in purposeless information searching, such as browsing purposeful information. A growing focus is also promoting interest in products and services by utilizing these opportunities. Thus, rather than the efficiency of information searching, the new concept of the “continuousness” of information searching is expected for information design. It has been suggested that searching for information without a defined purpose or use is done based on intrinsic motivation (IM). The theory of optimum stimulation level (SL) gives a U-shaped relationship between IM and SL. On the basis of this theory, we hypothesized that the continuousness of information is enhanced in an environment in which the user can enjoy searching for information at the optimum level of stimulation. In this study, we attempt to specify the requirements for a method of information design based on the aforementioned hypothesis. We assess the effectiveness of the method with an experiment in which participants engage in information browsing. The SLs of the referred pieces of information are quantified on a scale from zero to one. After analyzing the relationship between the SL and the physiological and psychological responses of the participants, we clarify (i) the optimum SL, (ii) the SL that most effectively enhances the IM of the participants to search for information, and (iii) the SL between one piece of information and the next at which the IM of the participants is increased.