Formation processes of high-mass stars have been long-standing issues in astronomy and astrophysics. This is mainly because of major diculties in observational studies such as a smaller number of high-mass young stellar objects (YSOs), larger distances, and more complex structures in young high-mass clusters compared with nearby low-mass isolated star-forming regions (SFRs), and extremely large opacity of in- terstellar dust except for centimeter to submillimeter wavelengths. High resolution and high sensitivity observations with Atacama Large Millimeter/Submillimeter Array (ALMA) at millimeter/submillimeter wavelengths will overcome these observational diculties even for statistical studies with increasing num- ber of high-mass YSO samples. This review will summarize recent progresses in high-mass star-formation studies with ALMA such as clumps and laments in giant molecular cloud complexes and infrared dark clouds (IRDCs), protostellar disks and out ows in dense cores, chemistry, masers, and accretion bursts in high-mass SFRs.
We have initiated a Very Long Baseline Interferometer (VLBI) monitoring project of 36 methanol maser sources at 6.7 GHz using the Japanese VLBI Network (JVN) and East-Asian VLBI Network (EAVN), starting in August 2010. The purpose of this project is to systematically reveal 3-dimensional (3-D) kine- matics of rotating disks around forming high-mass protostars. As an initial result, we present proper mo- tion detections for two methanol maser sources showing an elliptical spatial morphology, G 002.53+00.19 and G 006.79-00.25, which could be the best candidates associated with the disk. The detected proper motions indicate a simple rotation in G 002.53+00.19 and rotation with expansion in G 006.79-00.25, respectively, on the basis of disk model fits with rotating and expanding components. The expanding motions might be caused by the magnetic-centrifugal wind on the disk.