This application relates to a battery box, a battery, and an electric apparatus. A first end plate, a second end plate, and a first middle frame jointly enclose a semi-accommodating space with an opening at one end, and a height of the semi-accommodating space in an entry direction of a battery module entering the space is smaller than a height of the battery module in the direction, that is, the semi-accommodating space is shallower than the battery module. In this way, when the battery module is placed into the semi-accommodating space, it is less likely to fall and cause damage to the battery module. After the battery module is safely placed into the semi-accommodating space, a second middle frame is spliced with the first middle frame to seal the semi-accommodating space, thereby encapsulating the battery module.