Subsyndromal anxiety disorder indicates mental states of having anxiety symptoms not fulfilling criteria for anxiety disorders. Despite of the lack of previous objective findings of the subsyndromal anxiety disorder, its clinical importance has increased. It can cause many kinds of clinical anxiety symptoms and functional disabilities. But the early intervention and early treatment make it possible not only to attenuate the anxiety symptoms and functional disabilities but also to prevent disease progression to a full syndromal anxiety disorder. In this article, we will review the previous studies about the subsyndromal anxiety disorder and discuss its clinical characteristics and importance.