  The ``integral-shaped filament'' of the Orion A giant molecular cloud was
mapped in N2H+, and its northern end, the OMC-2/3 region was observed also in
HC3N and CCS. The N2H+ distribution is similar to the dust continuum
distribution, except for the central part of the Orion Nebula. The distribution
of H13CO+ holds resemblance to that of dust continuum, but the N2H+
distribution looks more similar to dust continuum distribution. The N-bearing
molecules, N2H+ and NH3 seem to be more intense in OMC-2, compared with the
H13CO+ and CS distribution. We identified 34 cloud cores from N2H+ data. Over
the Orion Nebula region, the N2H+ linewidth is large (1.1-2.1 km/s). In the
OMC-2/3 region, it becomes moderate (0.5-1.3 km/s), and it is smaller (0.3-1.1
km/s) in the south of the Orion Nebula. On the other hand, the gas kinetic
temperature of the quiescent cores observed in N2H+ is rather constant (~ 20 K)
over the $\int$-shaped filament. We detected no CCS emission in the OMC-2/3
region. In general, N2H+ and HC3N distribution is quite similar in the OMC-2/3
region, but we observed displacement between N2H+ and HC3N over 2' scale in
OMC-3, which has a chain of Class 0-I protostars (candidates).
