A mixer shaft for pre-wetting spraying apparatus is provided to allow simultaneous mixing and transferring materials for repairing or reinforcing concrete structure, and to reduce the amount of rebound and fine dust amount (scattered dust amount) during reinforcement. The mixer shaft for pre-wetting spraying apparatus includes: an axis part(100) formed in a rod shape and established rotatably within transferring pipe on silo outlet of the pre-wetting spraying apparatus; a spiral shaped blade established on the cylindrical surface of the axis part(100); and an assistant shaft(300) established rotatably on the axis part(100) with certain interval.
