The anti-van der Waerden number, denoted by aw([n], k), is the smallest r such that every exact r-coloring of [n] contains a rainbow k-term arithmetic progression. Butler et. al. showed that ⌈log 3 n⌉ + 2 ≤ aw([n], 3) ≤ ⌈log 2 n⌉ + 1, and conjectured that there exists a constant C such that aw ([n], 3) ≤ ⌈log 3 n⌉ + C. In this paper, we show this conjecture is true by determining aw ([n], 3) for all n. We prove that for 7 · 3 m−2 + 1 ≤ n ≤ 21 · 3 m−2 , aw([n], 3) = m + 2, if n = 3 m m + 3, otherwise.