An ultrasound observation apparatus comprising: a sheet including: a first transducer including a first upper electrode that is a GND electrode, a first piezoelectric element disposed on the first upper electrode, and a first lower electrode that is arranged in a predetermined arrangement direction on the first piezoelectric element and that is a positive electrode; a first transducer region in which the first transducer in plurality are arranged at predetermined intervals; a columnar portion in which at least a first surface is non-conductive, the columnar portion disposed adjacent to the first transducer positioned on a first end portion in the arrangement direction in the first transducer region; and a film portion that is flexible and that connects at least the first upper electrode in plurality in the first transducer region and a second surface facing the first surface of the columnar portion in the arrangement direction; and a bonding portion provided between the first transducer positioned on a second end portion in the arrangement direction among the first transducer in plurality in the first transducer region and the columnar portion and configured to maintain a state in which the sheet is rounded such that the film portion of the sheet becomes an external surface, and the first transducer positioned on the second end portion and the first surface of the columnar portion are attached to each other. a sheet including: a first transducer including a first upper electrode that is a GND electrode, a first piezoelectric element disposed on the first upper electrode, and a first lower electrode that is arranged in a predetermined arrangement direction on the first piezoelectric element and that is a positive electrode; a first transducer region in which the first transducer in plurality are arranged at predetermined intervals; a columnar portion in which at least a first surface is non-conductive, the columnar portion disposed adjacent to the first transducer positioned on a first end portion in the arrangement direction in the first transducer region; and a film portion that is flexible and that connects at least the first upper electrode in plurality in the first transducer region and a second surface facing the first surface of the columnar portion in the arrangement direction; and a first transducer including a first upper electrode that is a GND electrode, a first piezoelectric element disposed on the first upper electrode, and a first lower electrode that is arranged in a predetermined arrangement direction on the first piezoelectric element and that is a positive electrode; a first transducer region in which the first transducer in plurality are arranged at predetermined intervals; a columnar portion in which at least a first surface is non-conductive, the columnar portion disposed adjacent to the first transducer positioned on a first end portion in the arrangement direction in the first transducer region; and a film portion that is flexible and that connects at least the first upper electrode in plurality in the first transducer region and a second surface facing the first surface of the columnar portion in the arrangement direction; and a bonding portion provided between the first transducer positioned on a second end portion in the arrangement direction among the first transducer in plurality in the first transducer region and the columnar portion and configured to maintain a state in which the sheet is rounded such that the film portion of the sheet becomes an external surface, and the first transducer positioned on the second end portion and the first surface of the columnar portion are attached to each other.