Current mobile interaction is not well designed with considering mobility. Even though user attention is an important human factor for user interface design, current mobile service is too attentionconsuming for moving users to perform tasks. This is because mobile service is still pursuing desktop-miniaturization trend, and it is designed to work in stationary situations (e.g. "sitting on a chair", "standing on a street"). It makes mobile services not truly helpful in real mobile environments, since such situations are ideal and most of the time mobile users are in action while on the move. In this paper, we propose a dual-mode approach to design mobile services. Our approach aims to decrease a user's cognitive load by enabling users to retrieve information with less attention. The dual-mode approach provides a simplified interaction style (named simple interaction mode) to a mobile service, in addition to a conventional user interface (named normal interaction mode). While some of research activities aim to realize unobtrusive user interfaces for moving users, their advantages from conventional user interfaces have not been sufficiently evaluated. Therefore, we have prototyped a pedestrian navigation service in order to clarify feasibility of our approach.