Local leadership for global times

The present invention provides a nonwoven fabric made of fine denier filaments of superior bulkiness, heat insulation property and tensile strength, and a production method thereof. This nonwoven fabric is made of fine denier filaments produced by first preparing. First a thermoplastic polymer component "A", then another thermoplastic polymer component "B" which is insoluble in the component "A" and of which the melting point is higher than that of the component "A" by 30 DEG to 180 DEG C. Adopting a bicomponent melt spinning method employing the component "A" and the component "B", the bicomponent conjugate filaments, on which surface at least component "A" is exposed, are obtained. By accumulating these bicomponent conjugate filaments, a web is formed. Then heat is applied to the predetermined areas on the web throughout its entire thickness, whereby only the component A is softened or molten, and the bicomponent conjugate filaments are heat bonded to one another, thus a fleece is obtained. The predetermined areas are shaped like dots or lattices and distributed with a certain space between them. After obtaining the fleece, a wrinkling action is applied to the fleece.