A lens-fixing device, in which thermal caulking is performed on a lens frame to fix a lens to the lens frame, includes: a receiving base on which the lens frame equipped with the lens is disposed; a horn section disposed at a position opposite to the receiving base and pressing and deforming an end section of the lens frame while the lens frame disposed at the receiving base is heated; a moving section moving at least one of the receiving base and the horn section in a direction of an axis for performing the thermal caulking; and a positional adjusting section adjusting relative positions of the receiving base and the horn section in a direction perpendicular to the direction of the axis by moving the at least one of the receiving base and the horn section in the direction perpendicular to the direction of the axis.