[en] The 101-000 transition of para-formaldehyde (72.8381 GHz) has been observed for 10 points in Ori A by the 6-m millimeter-wave telescope at Mitaka. The emission has been found to be extended to the north direction compared with the 2-mm lines of formaldehyde; the north-south extension of the 73-GHz line emission is about 6'. The distribution of the excitation temperature of para-formaldehyde in the Orion molecular cloud is discussed. The column density of para-formaldehyde is estimated to be 2approx.5times1013 cm-2