The 2004 Japanese Invasive Alien Species Act was enacted to control invasive alien species (IASs) and to prevent damage caused by IASs to ecosystems. The Act represents a revolutionary advance for biological conservation in Japan. However, even 5 years have passed since the law enacted, no invasive alien species has succeeded to be eradicated. Even the prospects for control of the representative IASs, such as large-mouth bass, mongoose and European bumblebee, look dim in spite of great efforts by citizens, scientists and governments. The reasons for the failure of eradication or control of IASs are considered to be 1) the delay of accumulation and maintenance of biological data, 2) the delay of developing control methods adaptive to population dynamics of IASs, 3) the lack of tight network between organizations or projects eradicating IASs for cooperation and community of information, and 4) insufficient understanding of IAS problem among citizens and governments. Here we will analyze the state of control of IASs in Japan and will discuss the subjects to be resolved for reaching the goal of eradication.