  We found that at least 18 Young Stellar Object candidates invisible at
optical and near-infrared wavelengths, as well as ^12CO emission. They are IRAS
point sources with FIR colors similar to those of usual YSOs, and the infrared
spectral indices between 2.2 um and 25 um correspond to those of class I YSOs.
These peculiar far-infrared objects are highly concentrated around the galactic
plane and the distances are estimated to be around 1 kpc. Although their
distribution is away from molecular clouds, some of them seem to be associated
with large dark clouds or weak radio sources.
