A sealant hardening apparatus of an LCD panel and a sealant hardening method is disclosed, being suitable for decreasing a tact time, and for being easily applied to LCD panels of the different models, by irradiating UV rays in a scanning method, or by directly irradiating UV rays to a sealant pattern without using a mask, which includes a stage on which substrates bonded by a sealant are loaded, for being moved in an in-line method; a mask provided above the bonded substrates, having an open part corresponding to a sealant portion to transmit the light, and a closed part corresponding to the remaining portions to prevent the light; at least two align cameras for aligning the mask and the bonded substrates; a lamp for irradiating UV rays of high energy; a plurality of optical fibers for transmitting UV rays of the lamp; and a UV irradiation part for irradiating the UV rays from the optical fibers to the bonded substrates through the mask by arranging and supporting the optical fibers at one line.