  Dust continuum observation is one of the best methods to constrain the
properties of protoplanetary disks. Recent theoretical studies have suggested
that the dust scattering at the millimeter wavelength potentially reduces the
observed intensity, which results in an underestimate in the dust mass. We
investigate whether the dust scattering indeed reduces the observed continuum
intensity by comparing the ALMA archival data of the TW Hya disk at Band 3, 4,
6, 7 and 9 to models obtained by radiative transfer simulations. We find that
the model with scattering by 300 ${\rm \mu m}$-sized grains well reproduces the
observed SED of the central part of the TW Hya disk while the model without
scattering is also consistent within the errors of the absolute fluxes. To
explain the intensity at Band 3, the dust surface density needs to be $\sim$ 10
${\rm g\,cm^{-2}}$ at 10 au in the model with scattering, which is 26 times
more massive than previously predicted. The model without scattering needs 2.3
times higher dust mass than the model with scattering because it needs lower
temperature. At Band 7, scattering reduces the intensity by $\sim$ 35% which
makes the disk looks optically thin even though it is optically thick. Our
study suggests the TW Hya disk is still capable of forming cores of giant
planets at where the current solar system planets exist.
