Left: [J – H]/[H – K] color-color diagram of 2922 objects observed with S/N>10 at the K-band in the R CrA region. Circles and crosses show the objects identified as YSO candidates and background stars. Orange dashed lines show the intrinsic locus of CTTS, and blue solid and green solid lines show the intrinsic colors of main sequence stars and giants, respectively. An orange dash-dotted line shows the line that includes the 10σ color errors and reddening from the CTTS locus. Blue dotted lines represent the boundary of Class I and II, reddening vectors of main sequence stars and giant stars, from right to left. The black arrow shows the reddening vector of A_v = 5. Right: [J – H]/[H – K] color-color diagram of the reference field. Lines and markers are the same as the color-color diagram of the R CrA region. The black arrow shows the reddening vector of A_v = 5.