A gap inspection apparatus and a gap inspection method are disclosed. The gap inspection apparatus is configured for a wound battery cell, where in a height direction of the wound battery cell. The gap inspection apparatus includes: an X-ray source and an X-ray detector and a bearing mechanism located between the X-ray source and the X-ray detector. The bearing mechanism includes at least one accommodating groove, the accommodating groove is configured to accommodate the wound battery cell, and the height direction of the wound battery cell crosses a first direction in which the X-ray source points to the X-ray detector. The X-ray source is configured to irradiate an arc-shaped area of the wound body portion, and the X-ray detector is configured to obtain an imaging image of the irradiated arc-shaped area, so as to obtain a gap value between two electrode plates within the arc-shaped area.