The invention belongs to the field of accessories of two-wheeled electric vehicles, and in particular, provides a battery device of an automatic balance electric vehicle. The battery device comprises a battery box, and a square fixed frame with a slide rail; two ends of the battery box are erected on the slide rail, and the other two sides are connected with the square fixed frame through springs; first and second iron core coils are respectively arranged on two side surfaces of the square fixed frame; two ends of the first and second iron core coils are respectively connected with positive and negative pole circuits of the battery box to form a parallel relation; a first limiting switch is arranged on the circuit communicating with the first iron core coil; a second limiting switch is arranged on the circuit communicating with the second iron core coil; the first and second limiting switches are respectively fixed at two ends of the other slide rail; and a slide block is arranged on the slide rail. When the electric vehicle rolls, the slide block touches the first limiting switch; the first iron core coil is electrified to communicate with the circuit; the first iron core coil generates magnetic force to attract with the battery box; and the battery box moves in an opposite direction, so that the gravity center of the electric vehicle is balanced, and the electric vehicle is not liable to roll.