We present wide-field JHKs-band photometric observations of the three compact H II regions G48.9-0.3, G49.0-0.3, and G49.2-0.3 in the active star-forming region W51B. The star clusters inside the three compact H II regions show the excess number of stars in the J-Ks histograms compared with reference fields. While the mean color excess ratio (EJ-H/EH-Ks) of the three compact H II regions are similar to ~2.07 the visual extinctions toward them are somewhat different ~17 mag for G48.9-0.3 and G49.0-0.3; ~23 ≤ 2 Myr The inferred total stellar mass,~1.4x104M⊙, of W51B makes it one of the most active star forming regions in the Galaxy with the star formation efficiency of ~10%.

On behalf of the IRSF/SIRIUS group, I introduce some recent results from our deep near-infrared surveys (J, Hand Ks bands, limiting magnitude of Ks=17) toward star forming regions in the Milky Way Galaxy (MWG) and Large Magellanic Cloud (LMC) with the near-infrared camera SIRIUS. We discovered a rich population of low-mass young stellar objects associated with the W3 and NGC 7538 regions in the MWG based on the near-infrared colors arid magnitudes. The high sensitivity of our survey enables us to detect intermediate-mass pre-main sequence stars, i.e. HAEBE stars, even in the LMC. We detected many HAEBE candidate stars in the N159/N160 complex star forming region in the LMC with the IRSF 1.4-m telescope. Spatial distributions of the young stellar objects indicate the sequential cluster formation in each star forming region in the complex and large scale (a few X 100 pc) sequential cluster formation over the entire complex.