  We present the mid-infrared (MIR) light curves (LCs) of a tidal disruption
event (TDE) candidate in the center of a nearby ultraluminous infrared galaxy
(ULIRG) F01004-2237 using archival {\it WISE} and {\it NEOWISE} data from 2010
to 2016. At the peak of the optical flare, F01004-2237 was IR quiescent. About
three years later, its MIR fluxes have shown a steady increase, rising by 1.34
and 1.04 mag in $3.4$ and $4.6\mu$m up to the end of 2016. The host-subtracted
MIR peak luminosity is $2-3\times10^{44}$\,erg\,s$^{-1}$. We interpret the MIR
LCs as an infrared echo, i.e. dust reprocessed emission of the optical flare.
Fitting the MIR LCs using our dust model, we infer a dust torus of the size of
a few parsecs at some inclined angle. The derived dust temperatures range from
$590-850$\,K, and the warm dust mass is $\sim7\,M_{\odot}$. Such a large mass
implies that the dust cannot be newly formed. We also derive the UV luminosity
of $4-11\times10^{44}$\,erg\,s$^{-1}$. The inferred total IR energy is
$1-2\times10^{52}$\,erg, suggesting a large dust covering factor. Finally, our
dust model suggests that the long tail of the optical flare could be due to
dust scattering.
