An ultrasonic welding apparatus that performs an ultrasonic welding process to a sheet-like member, the sheet-like member being associated with an absorbent article, the sheet-like member being transported while being wound onto an outer circumferential face of a rotating member, the rotating member rotating about its central axis, the apparatus comprising: the rotating member; and an ultrasonic processing unit that rotates about the central axis together with the rotating member, and that includes, as ultrasonic processing members, a horn that vibrates ultrasonically and an anvil between which and the horn the sheet-like member is sandwiched; at least either one ultrasonic processing member of the horn and the anvil being guided so as to reciprocate in a CD direction, the CD direction intersecting a transport direction of the sheet-like member, the at least either one ultrasonic processing member of the horn and the anvil reciprocating in the CD direction with respect to a part of the sheet-like member, the part being wound around the rotating member, the outer circumferential face of the rotating member including a first section (A1a6) and a second section (A1a4) at positions different from each other in the CD direction, characterized in that the apparatus further comprises an ultrasonic-energy regulating unit, the ultrasonic-energy regulating unit making an amount (J/m) of ultrasonic energy applied per unit length in the CD direction when the ultrasonic processing member passes through the first section on either one of a forward path and a return path of the reciprocation different from an amount (J/m) of ultrasonic energy applied per unit length in the CD direction when the ultrasonic processing member passes through the second section on either one of the forward path and the return path. the rotating member; and an ultrasonic processing unit that rotates about the central axis together with the rotating member, and that includes, as ultrasonic processing members, a horn that vibrates ultrasonically and an anvil between which and the horn the sheet-like member is sandwiched; that rotates about the central axis together with the rotating member, and that includes, as ultrasonic processing members, a horn that vibrates ultrasonically and an anvil between which and the horn a horn that vibrates ultrasonically and an anvil between which and the horn the sheet-like member is sandwiched; at least either one ultrasonic processing member of the horn and the anvil being guided so as to reciprocate in a CD direction, the CD direction intersecting a transport direction of the sheet-like member, the at least either one ultrasonic processing member of the horn and the anvil reciprocating in the CD direction with respect to a part of the sheet-like member, the part being wound around the rotating member, the outer circumferential face of the rotating member including a first section (A1a6) and a second section (A1a4) at positions different from each other in the CD direction, characterized in that the apparatus further comprises an ultrasonic-energy regulating unit, the ultrasonic-energy regulating unit making an amount (J/m) of ultrasonic energy applied per unit length in the CD direction when the ultrasonic processing member passes through the first section on either one of a forward path and a return path of the reciprocation different from an amount (J/m) of ultrasonic energy applied per unit length in the CD direction when the ultrasonic processing member passes through the second section on either one of the forward path and the return path. an amount (J/m) of ultrasonic energy applied per unit length in the CD direction when the ultrasonic processing member passes through the first section on either one of a forward path and a return path of the reciprocation different from an amount (J/m) of ultrasonic energy applied per unit length in the CD direction when the ultrasonic processing member passes through the second section on either one of the forward path and the return path.