An object of the present invention is to provide an antiviral fiber assembly in which an antiviral agent is retained with chemical stability over a long period of time, and which is gentle to the human body. A further object of the present invention is to provide a fiber assembly with cellulose sulfate that can exhibit sufficient antiviral activity over a long period of time. Further, another object of the present invention is to provide a textile product obtained using such a fiber assembly.The present invention provides a fiber assembly with cellulose sulfate, wherein the hyaluronidase inhibitory activity is 50% or higher; and a process for producing a fiber assembly with cellulose sulfate, including treating a fiber assembly with an aqueous cellulose sulfate solution and drying, then treating the same with a pH buffer solution and drying.