Abstract: A belt guiding mechanism, for example for a child vehicle seat, which is suitable for guiding a belt extending through the belt guiding mechanism and locking said belt against movement. The belt guiding mechanism comprises a cam that is capable of pivoting movement relative to a bearing surface, said belt being movable in a tensioning direction and in the opposite direction through a passage present between said cam and said bearing surface. The cam is pivotable in a direction towards the hearing surface for locking the belt against movement. The cam is connected to a sleeve that can be positioned against a person's shoulder, in which sleeve the belt is slidably accommodated.