Provided are: a noise reduction device with an improved adhesion of objects formed of a porous material and with a reduced processing time; a method of manufacturing the noise reduction device; and a pneumatic tire including the noise reduction device. The noise reduction device of the present invention includes: objects formed of a porous material; a band member for attaching the objects to the inner surface of a tire at two positions spaced at substantially equal intervals in the tire circumferential direction; and locking members formed of a thermoplastic resin. The band member is formed of a thermoplastic resin. Each object is disposed at a predetermined position in the tire circumferential direction, between the band member and the corresponding locking members. The locking members are bonded to the band member through the objects by thermal fusion.