The objective of the present invention, in a back-massaging apparatus capable of projecting a massaging mechanism to the front and returning the same to the original position, is to be capable, upon securing an amount of motion that is sufficient, of achieving thinning in the front-to-rear direction of the back-massaging apparatus, and suppression of thickening of a backrest portion as a chair-type massager. A back massaging apparatus (4) of the present invention, which is provided to a chair-type massager (1), has: a massaging mechanism (10) which has massaging members (17), which are each provided with a treatment device (21) which performs massaging operation, and which are deployed in a pair on the left and right, and a drive unit (18) which transmits massaging operations to the massaging members (17) a base member (12) which supports the massaging mechanism (10) in a state in which the massaging members (17) face the front a vertical movement mechanism (13) which allows the base member (12) to move vertically within a backrest portion (3) and a variable projection amount mechanism (14) which moves the massaging members (17) so that the projection amounts in the front-to-rear direction of the treatment devices (21) change.Dans un appareil de massage de dos apte à projeter un mécanisme de massage à lavant et à le faire revenir dans la position dorigine, linvention vise à obtenir, lors de la fixation dune amplitude de mouvement qui est suffisante, lamincissement de lappareil de massage de dos dans la direction davant en arrière et la suppression de lépaississement dune partie dossier sous la forme dun appareil de massage du type chaise. Un appareil de massage de dos (4) de la présente invention, qui est disposé sur un appareil de massage du type chaise (1), comporte : un mécanisme de massage (10) qui a des éléments de massage (17), qui comprennent chacun un dispositif de traitement (21) qui exécute une opération de massage, et qui sont déployés par paire à gauche
