  We measured polarized dust emission at 350um towards the high-mass star
forming massive dense clump IRAS 20126+4104 using the SHARC II Polarimeter,
SHARP, at the Caltech Submillimeter Observatory. Most of the observed magnetic
field vectors agree well with magnetic field vectors obtained from a numerical
simulation for the case when the global magnetic field lines are inclined with
respect to the rotation axis of the dense clump. The results of the numerical
simulation show that rotation plays an important role on the evolution of the
massive dense clump and its magnetic field. The direction of the cold CO 1-0
bipolar outflow is parallel to the observed magnetic field within the dense
clump as well as the global magnetic field, as inferred from optical
polarimetry data, indicating that the magnetic field also plays a critical role
in an early stage of massive star formation. The large-scale Keplerian disk of
the massive (proto)star rotates in almost opposite sense to the clump's
envelope. The observed magnetic field morphology and the counter-rotating
feature of the massive dense clump system provide hints to constrain the role
of magnetic fields in the process of high mass star formation.
