アブストラクト：
The first data release of the Gaia have provided rich information on the Galactic halo substructures from stellar kinematics (e.g., Helmi et al. 2017). We compliment the kinematic data with the SAGA database, which contains chemical abundances of >1000 metal-poor stars based on high-resolution spectroscopy and is maintained by us. This addition of chemical information enables us to discuss the origin of the substructures from the point of chemical evolution. Although the combination of chemical and kinematic information has been limited to ~100 metal-poor stars so far due to the limitation of Gaia DR1, the planned Gaia data release 2 (25th April) is expected to revolutionize the situation. After this data release, we will be able to fully utilize kinematic and chemical information of ~1000 metal-poor stars in the SAGA database. In this workshop, we will show the first result from the combination of the SAGA database and Gaia DR2, and discuss the origin of the Galactic halo.