An X-ray tube, comprising: an anode including a target surface configured to radiate X-rays in a main radiation direction (d) from a first focal spot formed by collision of an electron beam; and a cathode arranged at a position opposite to the target surface of the anode, and including a first filament configured to emit the electron beam and a focusing electrode configured to focus the electron beam emitted from the first filament, the focusing electrode including a valley bottom part farthest from the first focal spot, a first inclined plane obliquely rising from the valley bottom part in the anode direction, a first focusing groove opened to the first inclined plane, and a first housing groove opened to a bottom surface of the first focusing groove to accommodate the first filament, wherein, if an axis passing through a center of the first focal spot and parallel to an X-ray tube axis is a reference axis, a plane including the reference axis and the main radiation direction (d) is a first reference plane, and an angle formed inside by a first extending line and a second extending line intersecting on a side opposite to a side of radiating the X-rays with respect to the reference axis is referred to as a first angle θ1, where the first extending line is a virtual straight line extending from a boundary straight line between the valley bottom part and the first inclined plane along the first reference plane, and the second extending line is a virtual straight line extending from the target surface along the first reference plane and the target surface, θ1>0°, the first housing groove has a long axis, and the other end part (31e2) of the first housing groove is closer to the first reference plane than one end part (31e1) of the first housing groove on the first extending line side; the first focusing groove has a long axis, and the X-ray tube is characterised in that the long axis of the first housing groove is inclined from the long axis of the first focusing groove. an anode including a target surface configured to radiate X-rays in a main radiation direction (d) from a first focal spot formed by collision of an electron beam; and a cathode arranged at a position opposite to the target surface of the anode, and including a first filament configured to emit the electron beam and a focusing electrode configured to focus the electron beam emitted from the first filament, the focusing electrode including a valley bottom part farthest from the first focal spot, a first inclined plane obliquely rising from the valley bottom part in the anode direction, a first focusing groove opened to the first inclined plane, and a first housing groove opened to a bottom surface of the first focusing groove to accommodate the first filament, wherein, if an axis passing through a center of the first focal spot and parallel to an X-ray tube axis is a reference axis, a plane including the reference axis and the main radiation direction (d) is a first reference plane, and an angle formed inside by a first extending line and a second extending line intersecting on a side opposite to a side of radiating the X-rays with respect to the reference axis is referred to as a first angle θ1, where the first extending line is a virtual straight line extending from a boundary straight line between the valley bottom part and the first inclined plane along the first reference plane, and the second extending line is a virtual straight line extending from the target surface along the first reference plane and the target surface, θ1>0°, the first housing groove has a long axis, and the other end part (31e2) of the first housing groove is closer to the first reference plane than one end part (31e1) of the first housing groove on the first extending line side; the first focusing groove has a long axis, and the X-ray tube is characterised in that the long axis of the first housing groove is inclined from the long axis of the first focusing groove.