  In this paper, we show the following three theorems. Let $G$ be a
$K_5$-minor-free graph. Then Alon-Tarsi number of $G$ is at most $5$, there
exists a matching $M$ of $G$ such that the Alon-Tarsi number of $G-M$ is at
most $4$, and there exists a forest $F$ such that the Alon-Tarsi number of
$G-E(F)$ is at most $3$.
