To provide an electrical junction box having a new structure that can be securely attached to a hole and can be readily removed even if a large clearance is required between the electrical junction box and a peripheral edge section around the attachment hole. An elastic projecting piece is integrally provided on a main body of an electrical junction box. The elastic projecting piece protrudes from an outer surface of the main body. The elastic projecting piece is provided with an engagement projection and an attachment projection that protrude outward from the main body opposite from each other in an extending direction of the elastic projecting piece to constitute an engagement fixing section. Elastic deformation of the elastic projecting piece permits the main body to be fitted into the attachment hole. A second inner peripheral edge portion around the attachment hole is clamped between the engagement and attachment projections.