Provided are an antibacterial fiber in which the amount of incorporation of an antibacterial glass is made sufficient with a small amount by reducing the content of the antibacterial glass in a core portion compared to the content of the antibacterial glass in a sheath portion, and which could exhibit excellent antibacterial properties； and an efficient method for producing such an antibacterial fiber. Disclosed is an antibacterial fiber containing a thermoplastic resin and an antibacterial glass as mixing components, the antibacterial fiber having an average diameter adjusted to a value within the range of 1 to 50 m, the antibacterial fiber including a core portion and a sheath portion, in which when a content of the antibacterial glass in the core portion is designated as Q1 (weight%) with respect to the total amount of the antibacterial fiber, and a content of the antibacterial glass in the sheath portion is designated as Q2 (weight%) with respect to the total amount of the antibacterial fiber, Q1 and Q2 satisfy the following relational expression (1): Q1 >； Q2 (1).本發明提供能夠通過使芯部的抗菌性玻璃的含量少於鞘部的抗菌性玻璃的含量而使抗菌性玻璃的配合量為少量即可、進而發揮優異的抗菌性的抗菌性纖維以及這樣的抗菌性纖維的有效的製造方法。所述抗菌性纖維包含熱塑性樹脂和抗菌性玻璃作為配合成分，使抗菌性纖維的平均直徑為1～50μm的範圍內的值，抗菌性纖維具備芯部和鞘部，使芯部的抗菌性玻璃的含量相對於抗菌性纖維的總量為Q1（重量％），且使鞘部的抗菌性玻璃的含量相對於抗菌性纖維的總量為Q2（重量％）時，Q1和Q2滿足下述關係式（1）。Q1＜Q2 （1）。
