  We present high-angular-resolution (1".5 - 5") interferometer observations of
the \co emission in the central region of the SA(s)c galaxy NGC 4254. The
observations were obtained using the Nobeyama Millimeter-wave Array (NMA)
during the course of a long-term CO line survey of Virgo spirals. We present
the spectra, channel maps, integrated intensity distributions, velocity fields,
position--velocity diagrams, and compare the data with various optical images.
The rotation velocity is already finite at the nucleus, or at least it rises
steeply to 80 km/s within the central 1", indicating the existence of a massive
core of 10^8 Msun within 1" (80 pc) radius. The CO intensity maps show that the
inner disk has well-developed multiple spiral arms, winding out from a
bar-shaped elongated molecular complex. In addition to the bisymmetric spiral
arms, an asymmetric tightly wound arm with high molecular gas density is found
to wind out from the molecular bar. The molecular spiral arms, particularly the
tightly wound arm, well traces optical dark lanes, and are associated with
H$\alpha$ arms having many H {\sc ii} regions. The inner asymmetric spiral
structures can be explained by ram-pressure distortion of inter-arm low density
regions of the inner disk by the intra-cluster gas wind, and is indeed
reproduced by a hydrodynamical simulation.
