There are provided: a compression plate for a medical imaging apparatus, which is used in a medical imaging apparatus including a radiation generation unit, a radiation detection unit, an ultrasound probe, and an imaging table disposed between the radiation generation unit and the radiation detection unit and which is used for compressing a subject by sandwiching the subject between the imaging table and the compression plate, the compression plate for a medical imaging apparatus including a polymethylpentene resin-containing material having a bending elastic modulus of 1 GPa or more and a thermal deformation temperature of 100° C. or higher, in which the polymethylpentene resin-containing material contains a polymethylpentene compound containing 1 to 300 ppm of a sulfur element based on mass; a polymethylpentene resin-containing material that is suitably used for the compression plate; and a medical imaging apparatus having the compression plate.