An electric connection box comprising: a housing having an opening formed by an upper end of each of a plurality of side walls; a lock protruding plate protruding on an outer surface of a first side wall of the plurality of side walls, the first side wall being along a side of the opening; a lid configured to be attached to the housing while covering the opening; a hook protruding downward from the lid; a lock portion provided on each of the lid and the housing; a protective wall protruding downward from the lid; a pair of lock pieces (25a, 25b) formed on side edges on both sides of the protective wall, the side edges being along a direction in which the protective wall extends; and a pair of slits (27a, 27b) provided on a second side wall of the plurality of side walls, wherein the hook is configured to rotate the lid such that the lid is attached to the housing with the hook being engaged with the locking protruding plate, wherein the lock portion is configured to fix the lid to the plurality of side walls, wherein the protective wall is configured to, when the lid is attached to the housing, cover a cable connection portion provided on the second side wall, wherein the pair of lock pieces (25a, 25b) extend in parallel with the protective wall and extend from the protective wall toward a first direction, wherein each of the pair of slits (27a, 27b) respectively includes a receiving opening configured to, when the lid is attached to the housing, accommodate respective one of the pair of lock pieces (25a, 25b), the pair of slits (27a, 27b) being configured to receive the respective one of the pair of lock pieces (25a, 25b) when engagement at the lock portion is carried out, and wherein the receiving opening opens, when the lid is attached to the housing, toward a second direction. a housing having an opening formed by an upper end of each of a plurality of side walls; a lock protruding plate protruding on an outer surface of a first side wall of the plurality of side walls, the first side wall being along a side of the opening; a lid configured to be attached to the housing while covering the opening; a hook protruding downward from the lid; a lock portion provided on each of the lid and the housing; a protective wall protruding downward from the lid; a pair of lock pieces (25a, 25b) formed on side edges on both sides of the protective wall, the side edges being along a direction in which the protective wall extends; and a pair of slits (27a, 27b) provided on a second side wall of the plurality of side walls, wherein the hook is configured to rotate the lid such that the lid is attached to the housing with the hook being engaged with the locking protruding plate, wherein the lock portion is configured to fix the lid to the plurality of side walls, wherein the protective wall is configured to, when the lid is attached to the housing, cover a cable connection portion provided on the second side wall, wherein the pair of lock pieces (25a, 25b) extend in parallel with the protective wall and extend from the protective wall toward a first direction, wherein each of the pair of slits (27a, 27b) respectively includes a receiving opening configured to, when the lid is attached to the housing, accommodate respective one of the pair of lock pieces (25a, 25b), the pair of slits (27a, 27b) being configured to receive the respective one of the pair of lock pieces (25a, 25b) when engagement at the lock portion is carried out, and wherein the receiving opening opens, when the lid is attached to the housing, toward a second direction.