The red dragon fruit is a popular fruit in Indonesia. The leather of red dragon fruit was not used optimally. The other case, the peel of red dragon fruit have a natural antimicrobe potency. This research have aim to eksplore the leather of red dragon fruit as an antimicrobe with used GC-MS. The result of research showed that content of the peel of red dragon fruit was dominated by ascorbic acid, oleic acid, decanoat, phenol and ester compound, that had an antimcrobe potency. The aplication of the peel of red dragon fruit on Tongkol fish that was contaminated with E coli, showed that, there is a decrease of E coli as much as 1.47 x 109 koloni/g, significantly. The conclusion of research was the peel of red dragon fruit have a natural antimicrobe potency.