A grass collecting assembly for a grass mower includes a bag holder provide in a strut unit supported to a vehicle body, a grass collecting bag attached to the bag holder, and a guide cover. The grass collecting bag has a bottom wall and a circumferential wall. An upper end of the circumferential wall forms an upper opening portion. The bottom wall is switchable between a discharging posture for downwardly discharging cut grass pieces accumulated in the grass collecting bag and an accumulating posture for accumulating cut grass pieces in the grass collecting bag. The guide cover guides cut grass pieces conveyed through a duct to the upper opening portion.
