The influence of the existence of an underlying SiO2 layer on the lateral solid-phase epitaxy (L-SPE) of amorphous Si was investigated by comparing the characteristics of L-SPE with and without an underlying SiO2 layer. For the L-SPE with an underlying SiO2 layer which had a change from (110) to {111} facet growth, high density crystal defects, most of which were dislocations, were detected especially in the {111} facet growth region. The formation of {111} facets is caused primarily by high density dislocations incorporated by relaxation of the stress which originates from the retardation of Si atom rearrangement. For the L-SPE without the underlying SiO2 layer, a few dislocations were detected only in the lower side of the L-SPE layer. The density of crystal defects did not increase during the L-SPE since the change from {110} to {111} facet growth was suppressed. Thus, we confirmed that removal of the underlying SiO2 layer prior to annealing for L-SPE dramatically reduces the crystal defects formed during L-SPE and halts the facet growth change from {110} to {111}.