The present invention provides a screw device enabling insulation of sounds occurring from the inside of the screw device when circulating rolling elements.The screw device includes: a screw shaft 1 having a spiral rolling-element rolling groove 1a on an outer circumferential surface; a nut body 2 having a spiral loaded rolling-element rolling groove 2a on an inner circumferential surface to oppose the rolling-element rolling groove 1a of the screw shaft 1 and having therein a rolling-element returning passage 6 to return rolling elements 3 rolling in a loaded rolling-element rolling passage 10 formed between the loaded rolling-element rolling groove 2a and the rolling-element rolling groove 1a of the screw shaft 1; a circulation member 9 attached to an end face of the nut body 2 and provided with a direction changing passage 5 to connect the loaded rolling-element rolling passage 10 and the rolling-element returning passage 6; and a sound insulating member 11 attached to the nut body 2 to which the circulation member 9 is attached and formed to have an inner circumferential surface coming into contact with the screw shaft and to cover the circulation member 9.