PURPOSE: To obtain the subject fiber, containing a specific phthalocyanine compound, having warmth retaining properties useful as arctic clothes, sports leisure clothes, interior articles such as curtains or leisure articles such as tents and producible with good productivity.

CONSTITUTION: This heat storage and warmth retaining fiber contains a phthalocyanine compound having the absorption peak in a near infrared region at ≥650nm. The content of the phthalocyanine compound in the fibrous material may be ≥1wt.% and sufficiently 0.01wt.% when the phthalocyanine compound is uniformly present in the fiber direction. A phthalocyanine compound of the formula [Y is (OCH2CH2)pW, etc.; W is a 1-4C alkoxy, etc.; (p) is an integer of 1-6; (a) to (d) are each an integer of 0-4; the sum total of (a) to (d) is 1-16; M is a metal, etc.], e.g. octafluoro-octakisanilinooxyvanadium phthalocyanine is preferred from the viewpoint of solubility and light fastness.