Energy transfer reactions from He(23S1) and Ne(3P0,2) to NH3 have been studied by observing emission spectra from excited fragments at crossed molecular beams. Metastable rare gas atoms are generated by dc. discharge in the molecular beams. NH(A-X,c-a,c-b), NH+(B-X) and H*-Balmer emission systems were observed in the He(23S1)reaction, while only NH(A-X,c-a) was observed in the Ne(3P0,2) reaction. The absolute cross section of NH(A,c) from He(23S1) was determined to be σ=0.56Å2 by using the reference-reaction method. The NH(c) has a large propensity to populate f rotational level in He(23s1)+NH3 reaction, and this is considered to come from a two-step dissociation process. The propensity is opposite to that of NH3 photolysis at 121.6nm The rotational excitation of NH(A,v=1) is somewhat higher than that of NH(A,v=0) and this may be the result of a large half-collision parameter according to the phase-space theory including angular momentum conversation. The ro-vibrational population of NH(A) and the rotational population of NH(c) can be interpreted with a simple phase-space theory of three-body dissociation in the reaction of Ne(3P0,2)+NH3.