An electrical connection box comprising: a housing member having an opening and an interior space connecting to the opening, the interior space accommodating an electrical connection part; a first cover member including a closure section that closes the opening and has a work opening enabling work relating to the electrical connection part; a second cover member configured to close the work opening; a hinge structure configured to allow the second cover member to rotate within a rotational range between an open position and a closed position relative to the work opening; and a detachment prevention structure configured to disable detachment of the second cover member from the first cover member in an assembled state in which the first cover member to which the second cover member is coupled is coupled to the housing member, wherein the hinge structure includes a rotation shaft provided on the closure section, an arc-shaped cantilever bearing provided on the second cover member, the bearing having an inner circumference surface supporting the rotation shaft, and a through hole formed in the closure section, the through hole accommodating the rotation shaft and being configured to allow the bearing to be inserted from a free end side and move in a direction that intersects an insertion direction of the bearing and is perpendicular to an axial direction of the rotation shaft to a shaft support position where the bearing is fitted to the rotation shaft, the detachment prevention structure includes a rotational retaining section provided on the bearing and a retainer provided on the housing member, the rotational retaining section being configured to stop rotation of the bearing relative to the rotation shaft, the retainer being configured to retain the bearing while permitting rotation of the bearing relative to the rotation shaft within the rotational range in the assembled state, and the retainer includes a first retaining section and a second retaining section, the first retaining section being configured to retain an outer circumferential surface of the bearing in the shaft support position regardless of a rotational position of the bearing relative to the rotation shaft within the rotational range, the second retaining section being configured to stop the rotational retaining section when the second cover member rotates from the closed position to the open position. a housing member having an opening and an interior space connecting to the opening, the interior space accommodating an electrical connection part; a first cover member including a closure section that closes the opening and has a work opening enabling work relating to the electrical connection part; a second cover member configured to close the work opening; a hinge structure configured to allow the second cover member to rotate within a rotational range between an open position and a closed position relative to the work opening; and a detachment prevention structure configured to disable detachment of the second cover member from the first cover member in an assembled state in which the first cover member to which the second cover member is coupled is coupled to the housing member, wherein the hinge structure includes a rotation shaft provided on the closure section, an arc-shaped cantilever bearing provided on the second cover member, the bearing having an inner circumference surface supporting the rotation shaft, and a through hole formed in the closure section, the through hole accommodating the rotation shaft and being configured to allow the bearing to be inserted from a free end side and move in a direction that intersects an insertion direction of the bearing and is perpendicular to an axial direction of the rotation shaft to a shaft support position where the bearing is fitted to the rotation shaft, the detachment prevention structure includes a rotational retaining section provided on the bearing and a retainer provided on the housing member, the rotational retaining section being configured to stop rotation of the bearing relative to the rotation shaft, the retainer being configured to retain the bearing while permitting rotation of the bearing relative to the rotation shaft within the rotational range in the assembled state, and the retainer includes a first retaining section and a second retaining section, the first retaining section being configured to retain an outer circumferential surface of the bearing in the shaft support position regardless of a rotational position of the bearing relative to the rotation shaft within the rotational range, the second retaining section being configured to stop the rotational retaining section when the second cover member rotates from the closed position to the open position.