To provide high filter properties and excellent shape stability by using a microweb sheet with a density of a specified value as an intermediate layer, arranging a woven fabric with a specified cover factor on one face of the intermediate layer and a knitted fabric with a gas permeability of at least a specified value on another face and bonding partly adjoining cloths.

A three-layer composite structural cloth 1 is a laminated cloth formed by bonding partly cloths with three different functions. As an intermediate layer 2, a microweb sheet with a density of 0.10-0.20g/cm3 is used. On one face of the intermediate layer 2, a fabric 4 with a cover factor of 1,300-1,800 and with a texture density with no stitch deviation is arranged and on another face, a knitted fabric 3 with a gas permeability of at least 30cc/cm2/sec is arranged. Bondings 5 between the intermediate layer 2 and the woven fabric and between it and the knitted fabric 3 are partly bonded and an ultrasonic welder with no limitation in regard to the kind of fiber raw material is used for the partial bonding which can hold durability of bonding without obstructing the original gas permeability of the microweb sheet 2.