We found a unique horizontal transfer phenomenon of BovB LINE having a strange direction, from snakes to frogs. To estimate the frequency, phylogeny, age, and region of this horizontal transfer event, we collected more than 100 snake and frog taxa from many regions of the world. From these specimens, BovB was PCR amplified and their amplicon sequences were determined using NGS (mainly PacBio RS II). In addition, since direct horizontal transfer of BovB from snakes to frogs is unlikely, we collected parasites (belonging to four distinct animal phyla) that may have mediated the BovB transfer. By PCR survey, we identified the parasites having snake-type BovB and sequenced the paracites' BovB sequences. Finally, based on these BovB sequence data, we demonstrate that the hot spot of this horizontal transfer and the presence rate of BovB positive parasites effect the frequency of BovB transfer from snakes to frogs.