  We present a host morphological study of 1266 far-infrared galaxies (FIRGs)
and submillimeter galaxies (SMGs) in the Cosmic Evolution Survey field using
the F160W and F814W images obtained by the Hubble Space Telescope. The FIRGs
and SMGs are selected from the Herschel Multi-tiered Extragalactic Survey and
the SCUBA-2 Cosmology Legacy Survey, respectively. Their precise locations are
based on the interferometry data from the Atacama Large
Millimeter/submillimeter Array and the Very Large Array. These objects are
mostly at $0.1\lesssim z\lesssim 3$. The SMGs can be regarded as the population
at the high-redshift tail of the FIRGs. Most of our FIRGs/SMGs have a total
infrared luminosity ($L_{\rm IR}$) in the regimes of luminous and ultraluminous
infrared galaxies (LIRGs, $L_{\rm IR} = 10^{11-12}L_\odot$; ULIRGs, $L_{\rm
IR}>10^{12}L_\odot$). The hosts of the SMG ULIRGs, FIRG ULIRGs, and FIRG LIRGs
are of sufficient numbers to allow for detailed analysis, and they are only
modestly different in their stellar masses. Their morphological types are
predominantly disk galaxies (type D) and irregular/interacting systems (type
Irr/Int). There is a morphological transition at $z\approx 1.25$ for the FIRG
ULIRG hosts, above which the Irr/Int galaxies dominate and below which the D
and Irr/Int galaxies have nearly the same contributions. The SMG ULIRG hosts
seem to experience a similar transition. This suggests a shift in the relative
importance of galaxy mergers/interactions versus secular gas accretions in
"normal" disk galaxies as the possible triggering mechanisms of ULIRGs. The
FIRG LIRG hosts are predominantly D galaxies over $z=$ 0.25--1.25, where they
are of sufficient statistics.
