<p> It is a social challenge to maintain the mental and physical health of workers, to motivate them, and to improve their intellectual productivity in order to achieve sustainable economic growth. Many studies are currently being conducted under the assumption that an office space’s design, including thermal environment, sound environment, etc., influences the intellectual productivity of its workers. The understanding of such a relationship is becoming increasingly important due to the introduction of new styles of working, such as activity-based working (ABW) that enables workers to select a seat that matches their work or preference, and this is gaining research attention. Previous studies have found that interactive sounds heard from a conference space in an open plan office interfere with workers' workability. Therefore, it is necessary to evaluate not only the sound environment but also the comprehensive indoor environment in an ABW office to ensure that there is a space with an environment suitable for each task.</p><p> In this study, we investigated office workers’ satisfaction to compare satisfaction levels and intellectual productivity of the workers in an ABW office and a conventional office. Based on the results from questionnaires, changes were made to the layout of the ABW office to resolve sources of dissatisfaction. A questionnaire and field survey were conducted once more to evaluate the effects of this remodeling, and the ABW and conventional offices were compared again.</p><p> Based on the indoor environment satisfaction levels, it was hypothesized that it is important to increase the number of ‘concentration’ seats and to consider the sound environment to improve intellectual productivity. In the questionnaire, it was found that as communication and individual space satisfaction decreased more ABW office workers reported a decrease in their work efficiency. It turned out that simply introducing ABW into an office does not necessarily contribute to work efficiency and intellectual productivity improvements. As a result of improving the layout according to the expected amount of communication required with high partitions to block line of sight and sound, an increase in work efficiency was reported compared with the ABW office before the improvements. Although we examined the satisfaction of each environment, significant differences were not seen in each of the environments among ABW offices. Since comparisons were made within a small room with the same number of people and objects, changes in congestion state of seats, sound environment, etc. may have been insufficient. For example, there is a possibility that there was not enough unevenness of environment, such as a quiet environment and a lively environment, and the environment did not suit personal preferences.</p><p> From the above, we found that in order to improve intellectual productivity it was necessary not only to introduce various furniture and free seats, but also to change space planning and the working style itself according to anticipated actions. For instance, it is not convenient to use paper documents if working staffs keep moving, so it is necessary to digitally document the paper used in the an ABW office. In order to improve intellectual productivity, it is necessary to pay attention to the number of seats, the sound environment, the spatial environment, and more.</p>