An inexpensive fiber that has heat retaining properties, satisfactory weather resistance and heat absorption efficiency, and includes a heat absorbing material having excellent transparency; and a fiber article that uses the fiber. A particle dispersion of Cs.sub.0.33WO.sub.3 is obtained by mixing Cs.sub.0.33WO.sub.3 microparticles, toluene, and a microparticle dispersing agent to create a liquid dispersion, and then removing the toluene. The particle dispersion is added to and uniformly mixed with pellets of polyethylene terephthalate resin, after which the mixture is extruded, the strands thus obtained are formed into pellets, and a master batch including Cs.sub.0.33WO.sub.3 microparticles is obtained. This master batch is mixed with a master batch to which inorganic microparticles have not been added, and the mixture thus obtained is melt spun and stretched to manufacture a polyester multifilament yarn. The polyester multifilament yarn is cut, polyester staple fibers are created, and a spun yarn is manufactured. A heat retentive knit article is obtained using the spun yarn.