封手是指在棋类比赛中的一种规则，指当比赛时间超过一天时，在前一天对局时间到时，轮到的一方要将想要下的棋步写在纸上，等到第二天开始时才公布封手的棋步再继续棋局。

封手规则的目的，在于不让任何一方可以趁休息的时间，有较多的时间来考虑下一步的下法，封手的一方因先决定下法而不能改变，另一方则因为不知道对方封手的棋步而不易作接下来棋步的思考。

目前日本围棋与将棋部份的头衔战对局时间为两天，即采用封手的制度。

Some board games, such as chess and Go, use an adjournment mechanism to suspend the game in progress so it can be continued at another time, typically the following day. The rationale is that games often extend in duration beyond what is reasonable for a single session of play. As in chess, there is sometimes a sealed move, where the next move that would be made is sealed in an envelope, to be played out when the game resumes (normally played by the director or arbiter). This practice ensures that neither player knows what the board position will be when it is their next turn to move.