A display device comprising: a display configured to display an image on a display surface; a rear cover disposed on a rear side of the display; one or more first speaker disposed between the display and the rear cover; and one or more second speaker disposed between the display and the rear cover and positioned higher than the one or more first speaker, wherein the one or more second speaker has a higher audio output band than the one or more first speaker, characterized in that the one or more second speaker each comprises: a case body constituted by a rear surface part, a side surface part, a top surface part, a bottom surface part, a connection part and a reinforcement part, the side surface part being continuous with one side edge of the rear surface part, the top surface part and the bottom surface part respectively being continuous with a top edge and a bottom edge of the rear surface part, one side edge of the top surface part and one side edge of the bottom surface part being continuous with top and bottom edges, respectively, of the side surface part, the connection part connecting another end of the top surface part with another end of the bottom surface part, and being located in front of the rear surface part; a diaphragm being bonded to an inner surface of the rear surface part; a piezoelectric element affixed to a front surface of the diaphragm and configured to operate by application of a voltage, wherein the diaphragm is configured to vibrate according to operation of the piezoelectric element; and an audio passage hole formed in the case body, wherein the audio passage hole is surrounded by the rear surface part, the top surface part, the bottom surface part and the connection part, wherein the audio passage hole is located opposite to the side surface part, wherein the reinforcement part is provided in a central part of the audio passage hole and connects the rear surface part to the connection part, and wherein output audio passes through the audio passage hole. a display configured to display an image on a display surface; a rear cover disposed on a rear side of the display; one or more first speaker disposed between the display and the rear cover; and one or more second speaker disposed between the display and the rear cover and positioned higher than the one or more first speaker, wherein the one or more second speaker has a higher audio output band than the one or more first speaker, characterized in that the one or more second speaker each comprises: a case body constituted by a rear surface part, a side surface part, a top surface part, a bottom surface part, a connection part and a reinforcement part, the side surface part being continuous with one side edge of the rear surface part, the top surface part and the bottom surface part respectively being continuous with a top edge and a bottom edge of the rear surface part, one side edge of the top surface part and one side edge of the bottom surface part being continuous with top and bottom edges, respectively, of the side surface part, the connection part connecting another end of the top surface part with another end of the bottom surface part, and being located in front of the rear surface part; a diaphragm being bonded to an inner surface of the rear surface part; a piezoelectric element affixed to a front surface of the diaphragm and configured to operate by application of a voltage, wherein the diaphragm is configured to vibrate according to operation of the piezoelectric element; and an audio passage hole formed in the case body, wherein the audio passage hole is surrounded by the rear surface part, the top surface part, the bottom surface part and the connection part, wherein the audio passage hole is located opposite to the side surface part, wherein the reinforcement part is provided in a central part of the audio passage hole and connects the rear surface part to the connection part, and wherein output audio passes through the audio passage hole. a case body constituted by a rear surface part, a side surface part, a top surface part, a bottom surface part, a connection part and a reinforcement part, the side surface part being continuous with one side edge of the rear surface part, the top surface part and the bottom surface part respectively being continuous with a top edge and a bottom edge of the rear surface part, one side edge of the top surface part and one side edge of the bottom surface part being continuous with top and bottom edges, respectively, of the side surface part, the connection part connecting another end of the top surface part with another end of the bottom surface part, and being located in front of the rear surface part; a diaphragm being bonded to an inner surface of the rear surface part; a piezoelectric element affixed to a front surface of the diaphragm and configured to operate by application of a voltage, wherein the diaphragm is configured to vibrate according to operation of the piezoelectric element; and an audio passage hole formed in the case body, wherein the audio passage hole is surrounded by the rear surface part, the top surface part, the bottom surface part and the connection part, wherein the audio passage hole is located opposite to the side surface part, wherein the reinforcement part is provided in a central part of the audio passage hole and connects the rear surface part to the connection part, and wherein output audio passes through the audio passage hole.