Anomalous Nernst effect in the nonmagnetic nodal-line semimetal PbTaSe2

${\mathrm{PbTaSe}}_{2}$ is a unique topological material, in which the number of nodal lines is expected to change at the structural transition between the lower-temperature/pressure L phase and the higher-temperature/pressure H phase. We report the anomalous Nernst effect attributed to the Berry curvature of nodal lines and its change with the structural transition. In the L phase, the Nernst coefficient (${S}_{yx}$) shows a steplike magnetic field dependence reminiscent of the anomalous Nernst effect of nonmagnetic Dirac/Weyl semimetals. By applying hydrostatic pressure, we discovered that the amplitude of the anomalous component markedly decreases at the transition to the H phase, which might correspond to the partial annihilation of nodal-line structures.