A weather strip assembly for applying to opposite swing doors configured such that a front end portion of a front door and a rear end portion of a rear door of the opposite swing doors are rotatably connected to a vehicle body respectively to allow sides of a vehicle to be open or closed and airtightly sealing a rear end portion of the front door and a front end portion of the rear door, may include a main sealing member mounted to rotate between the rear end portion of the front door and the front end portion of the rear door to airtightly seal between the rear end portion of the front door and the front end portion of the rear door while rotating when one of the front and rear doors is opened or closed.