Restraining harness for a vehicle seat, comprising - a portion for being fitted to a backrest, which is configured to be fitted to a backrest of a vehicle seat, - a portion for being fitted to a posture, which is configured to be fitted to a torso of a user so as to restrain the user on the seat, the portion for being fitted to a posture being secured to the portion for being fitted to a backrest, the harness further comprising - a locking system (B; BL) which is configured to receive at least one part (PS, PI) of the portion for being fitted to a backrest, the locking system (B; BL) comprising at least one release button or at least one release lever, and a locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest and release it when the release button is pressed or pulled or the release lever is raised, the release button or release lever being configured to be arranged out of reach of the user on the seat; characterized in that the locking system comprises a safety housing which is configured to receive the part (PS, PI) of the portion for being fitted to a backrest, the housing comprising at least one release strap and the locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest, the locking mechanism being configured to release the part of the portion for being fitted to a backrest when the release strap is pulled. - a portion for being fitted to a backrest, which is configured to be fitted to a backrest of a vehicle seat, - a portion for being fitted to a posture, which is configured to be fitted to a torso of a user so as to restrain the user on the seat, the portion for being fitted to a posture being secured to the portion for being fitted to a backrest, the harness further comprising - a locking system (B; BL) which is configured to receive at least one part (PS, PI) of the portion for being fitted to a backrest, the locking system (B; BL) comprising at least one release button or at least one release lever, and a locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest and release it when the release button is pressed or pulled or the release lever is raised, the release button or release lever being configured to be arranged out of reach of the user on the seat; characterized in that the locking system comprises a safety housing which is configured to receive the part (PS, PI) of the portion for being fitted to a backrest, the housing comprising at least one release strap and the locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest, the locking mechanism being configured to release the part of the portion for being fitted to a backrest when the release strap is pulled. the harness further comprising - a locking system (B; BL) which is configured to receive at least one part (PS, PI) of the portion for being fitted to a backrest, the locking system (B; BL) comprising at least one release button or at least one release lever, and a locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest and release it when the release button is pressed or pulled or the release lever is raised, the release button or release lever being configured to be arranged out of reach of the user on the seat; - a locking system (B; BL) which is configured to receive at least one part (PS, PI) of the portion for being fitted to a backrest, the locking system (B; BL) comprising at least one release button or at least one release lever, and a locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest and release it when the release button is pressed or pulled or the release lever is raised, the release button or release lever being configured to be arranged out of reach of the user on the seat; characterized in that the locking system comprises a safety housing which is configured to receive the part (PS, PI) of the portion for being fitted to a backrest, the housing comprising at least one release strap and the locking mechanism which is configured to secure the part (PS, PI) of the portion for being fitted to a backrest, the locking mechanism being configured to release the part of the portion for being fitted to a backrest when the release strap is pulled.