An ultrasonic endoscope comprising: an insertion unit to be inserted into an inside of the body; a distal end part body provided to a distal end of the insertion unit; an ultrasonic observation unit provided to the distal end part body; an ultrasonic oscillator provided to the ultrasonic observation unit and including an observation surface through which ultrasonic waves are communicated, side surfaces adjacent (80B-80E) to the observation surface, a bottom surface opposite to the observation surface, a piezoelectric element provided closer to the observation surface, and a backing material provided to the bottom surface of the piezoelectric element; a wiring connection unit provided to the ultrasonic oscillator and connected with wiring for supplying a drive voltage to the ultrasonic oscillator; an ultrasonic-oscillator housing part covering the side surfaces (80B-80E) and the bottom surface of the ultrasonic oscillator, housing the ultrasonic oscillator, and including a wire housing space in which the wiring is housed, on a side on which the bottom surface of the ultrasonic oscillator is housed; an acoustic lens made of resin covering the observation surface of the ultrasonic oscillator and adhered to the ultrasonic-oscillator housing part; and a sealing member that seals a gap formed between the ultrasonic oscillator and the ultrasonic-oscillator housing part, characterized in that the sealing member has a uniform thickness in a normal direction of a surface of the sealing member, which is in contact with a corresponding one of the side surfaces (80B-80E) of the ultrasonic oscillator when the ultrasonic oscillator is housed in the ultrasonic-oscillator housing part, and the sealing member is elastic in a thickness direction corresponding to the normal direction. an insertion unit to be inserted into an inside of the body; a distal end part body provided to a distal end of the insertion unit; an ultrasonic observation unit provided to the distal end part body; an ultrasonic oscillator provided to the ultrasonic observation unit and including an observation surface through which ultrasonic waves are communicated, side surfaces adjacent (80B-80E) to the observation surface, a bottom surface opposite to the observation surface, a piezoelectric element provided closer to the observation surface, and a backing material provided to the bottom surface of the piezoelectric element; a wiring connection unit provided to the ultrasonic oscillator and connected with wiring for supplying a drive voltage to the ultrasonic oscillator; an ultrasonic-oscillator housing part covering the side surfaces (80B-80E) and the bottom surface of the ultrasonic oscillator, housing the ultrasonic oscillator, and including a wire housing space in which the wiring is housed, on a side on which the bottom surface of the ultrasonic oscillator is housed; an acoustic lens made of resin covering the observation surface of the ultrasonic oscillator and adhered to the ultrasonic-oscillator housing part; and a sealing member that seals a gap formed between the ultrasonic oscillator and the ultrasonic-oscillator housing part, characterized in that the sealing member has a uniform thickness in a normal direction of a surface of the sealing member, which is in contact with a corresponding one of the side surfaces (80B-80E) of the ultrasonic oscillator when the ultrasonic oscillator is housed in the ultrasonic-oscillator housing part, and the sealing member is elastic in a thickness direction corresponding to the normal direction.