The present invention relates to a breastrest detachably installed on a chair back, and more particularly, a fixing body detachably coupled to a rear of a chair back, and installed in both lengthwise directions of the fixing body, respectively, left and right and up and down directions. A fixed bar movably fixed to the first bar, one end of which is coupled to one end of the fixed bar, the first rotating member being pivoted to the side of the chair back with the longitudinal direction of the fixed bar axially； A second rotation member rotatably coupled to the other end of the first rotation member, the second rotation member pivoted in the longitudinal direction of the first rotation member, and a cushion pad having a cushion and coupled to the other end of the second rotation member. Including, the fixing body is fixed to the rear of the chair back, the first rotating member is rotated without interference from the side of the chair back After fixing the fixing bar by adjusting the position, the first pivot member is rotated from the rear of the chair back to the front of the chair back via the upper part, and then the second pivot member is rotated to the inside of the chair back to cushion the cushion. The pads are placed on the chest of the person seated on the chair. According to the present invention as described above, can be used to install the detachable breastrest on the chair with the back, even if the mounting position of the fixed body is limited according to the shape of the various chairs, by re-adjusting the position of the fixed bar separately The cushion pad can be placed on the seat of the seat of the seat, especially the upper part of the chest to support the woman without discomfort, the upper chest is supported to relieve the burden on the neck shoulders, Applicable to most chairs, the range of use is very wide. In addition, when the chestrest is needed, the backrest of the backrest is pivoted forward and the two-stage pivoting structure allow
