A work vehicle cooperation system includes: a master traveling tack calculation unit that calculates a traveling track of a master work vehicle (1P) based on its position; a loop traveling detection unit that detects loop traveling in a loop work area (B); a redirection traveling target calculation unit that calculates a redirection traveling start point and a redirection traveling end point (Pc3) of a slave work vehicle (1C) based on a redirection traveling track including a redirection traveling start point (Pp1) and a redirection traveling end point of redirection traveling of the master work vehicle (1P); and a loop work traveling target calculation unit that calculates a target traveling position in loop work traveling of the slave work vehicle (1C) for the redirection traveling end point (Pc3) to a next redirection traveling start point (Pc1).