To provide a bristle for a toothbrush of a sea-island structure using a PPT (polytrimethylene terephthalate) resin for a sea part and having a high bending recovery and shatter resistance and to provide a toothbrush using the same.

Island fibers 3 composed of a polyamide resin are disposed in a sea part 2 composed of a polytrimethylene terephthalate (PTT) resin along the outer circumference of the sea part at an approximately equal interval. The shortest distance (m) between the island fiber and the bristle surface is defined to 10-30 μm and the shortest distance (n) between the island fibers is defined within a range of 10-50 μm. The cross sectional shape of the island fiber 3 is either of a circle or an ellipse and the elliptical cross-section island fiber is so disposed that the direction of the long axis of the elliptical cross section is approximately accorded with the tangential direction of a concentric circle drawn around a bristle axis.