Tongue for a child restraint system and child restraint system

To provide a child restraint tongue capable of joining left and right tongue plates together easily and tightly and a child restraint system including the child restraint tongue. A child restraint tongue 10 includes a pair of left and right detachable tongue plates 20 and 30. The tongue plates 20 and 30 include magnets 21 and 31 for joining them together by attraction, respectively. The opposing faces of the respective holding portions 23 and 33 of the left and right tongue plates 20 and 30 form linear guide surfaces 23a and 33a, respectively, which attach closely with each other. The magnets 21 and 31 are embedded in the guide surfaces 23a and 33a, respectively.