  We present results from a 50 ks observation of the narrow-line Seyfert 1
galaxy Ark 564 with the Chandra HETGS. The spectra above 2 keV are modeled by a
power-law with a photon-index of 2.56+/-0.06. We confirm the presence of the
soft excess below about 1.5 keV. If we fit the excess with blackbody model, the
best-fit temperature is 0.124 keV. Ark 564 has been reported to show a peculiar
emission line-like feature at 1 keV in various observations using lower
resolution detectors, and the Chandra grating spectroscopy rules out an origin
of blends of several narrow emission lines. We detect an edge-like feature at
0.712 keV in the source rest frame. The preferred interpretation of this
feature is combination of the O VII K-edge and a number of L-absorption lines
from slightly ionized iron, which suggests a warm absorber with ionization
parameter xi~1 and N_H ~ 10^21 cm^-2. These properties are roughly consistent
with those of the UV absorber. We also detect narrow absorption lines of O VII,
O VIII, Ne IX, Ne X, and Mg XI at the systemic velocity. From these lines, a
second warm absorber having log xi ~ 2 and N_H ~ 10^21 cm^-2 is required.
