PURPOSE: To provide a soundproof unit with good sealing property and high sound insulating effect with a simple work by fitting a lower sound insulating member to an upper sound insulating member to form a double sound insulating wall.

CONSTITUTION: A lower sound insulating member 10 has a bottom plate 1 for placing an equipment 30 forming a noise source and a cylindrical first sound insulating wall 12 surrounding the circumference of the equipment 30, which are integrally formed. The first sound insulating wall 12 has a box form in which the upper part is opened in the state vertically stood on the surface of the bottom plate 11. An upper sound insulating member 20 has a top plate 21 for covering the opening part of the first sound insulating member 12 and a cylindrical second sound insulating wall 22 surrounding the circumference of the equipment 30 in the inner circumferential part of the first sound insulating wall 12, which are integrally formed. The second sound insulating wall 22 has a form smaller than the cross sectional form of the first sound insulating wall 12, so that it is situated on the inner circumferential part of the first sound insulating wall 12 when fitted. Thus, the second sound insulating wall 22 also has a box form having an opening in the lower part in the state stood on the top plate 21. Thus, a soundproof unit having high sound insulating effect can be provided.