A printer , comprising: a medium supply unit configured to supply a print medium (P); feeding means configured to feed the print medium (P) supplied from the medium supply unit along a medium feed path; a printing head portion disposed in the medium feed path, the printing head portion being configured to open/close; printing means disposed at the printing head portion to print on the print medium (P) fed along the medium feed path; a damper portion disposed between the medium supply unit and the printing head portion in the medium feed path, the damper portion being configured to swing in order to give tension to the print medium (P), the damper portion being disposed to open above when the printing head portion opens; a first support body configured to support the printing head portion , the printing head portion being configured to open/close; a second support body configured to support the damper portion , the damper portion being configured to open/ close; a spring configured to bias the second support body in an opening direction; a suppression portion disposed at the first support body , the suppression portion being configured to suppress an opening operation of the second support body against biasing force of the spring in a closed state of the printing head portion ; and an induction portion disposed at the second support body , the induction portion being configured to guide the suppression portion to the suppression release position in an opening operation of the printing head portion and guide the suppression portion to the suppression position in a closing operation of the printing head portion . a medium supply unit configured to supply a print medium (P); feeding means configured to feed the print medium (P) supplied from the medium supply unit along a medium feed path; a printing head portion disposed in the medium feed path, the printing head portion being configured to open/close; printing means disposed at the printing head portion to print on the print medium (P) fed along the medium feed path; a damper portion disposed between the medium supply unit and the printing head portion in the medium feed path, the damper portion being configured to swing in order to give tension to the print medium (P), the damper portion being disposed to open above when the printing head portion opens; a first support body configured to support the printing head portion , the printing head portion being configured to open/close; a second support body configured to support the damper portion , the damper portion being configured to open/ close; a spring configured to bias the second support body in an opening direction; a suppression portion disposed at the first support body , the suppression portion being configured to suppress an opening operation of the second support body against biasing force of the spring in a closed state of the printing head portion ; and an induction portion disposed at the second support body , the induction portion being configured to guide the suppression portion to the suppression release position in an opening operation of the printing head portion and guide the suppression portion to the suppression position in a closing operation of the printing head portion . <EOS>