A method of manufacturing an active matrix electrochromic device includes preparing a first substrate including a thin film transistor including a gate electrode, a source electrode, and a drain electrode, and a pixel electrode electrically connected to the drain electrode. An electrochromic layer is formed on the pixel electrode by an electrophoretic process which includes immersing the first substrate and a mesh spaced apart from each other in a solution. While the first substrate is immersed in the solution so that the pixel electrode is soaked therein, a channel of the thin film transistor is opened by applying a voltage to the gate electrode, a potential difference between the pixel electrode and the mesh is generated by connecting a voltage source between a terminal electrically connected to the source electrode and the mesh, and materials in the solution are deposited on the pixel electrode, thereby forming the electrochromic semiconductor layer.