To solve the problem such that various proposals are made as a fiber imparted with electroconductivity by complexing the fiber with an electron conjugated polymer, such as the fiber made by complexing a polypyrrole which is the electron conjugated polymer after dyeing an acrylic fiber, the fiber complexed with the pyrrole-based polymer after neutralizing a vinylon fiber with an organic compound having sulfonic acid group, or the like, however, in these fibers, the electroconductive coating films have low strength and easily fall off.

The electroconductive fiber is a fiber containing a vinyl-based polymer having a sulfonic acid group, wherein the fibers having 0.1 mmol/g of sulfonic acid groups to the weight of the fibers are coated with the electron conjugated polymer and the sulfonic acid group and the electron conjugated polymer are ionically bonded.