Rules · 反則 hansoku
The moves you may not play.
Shogi has only a handful of illegal moves, and most beginners meet them the same way: a dropped pawn that looked like a brilliant finish, or a second pawn on a file they forgot they had. Here is each one, on a board, with the move that looks almost the same and is allowed.
An illegal move loses
In casual chess an illegal move is usually just taken back. In shogi it is 反則負け (hansoku-make): in a professional or tournament game, the player who makes it loses on the spot. Between friends you may agree otherwise, and some apps simply refuse the move. Shogi Castle is one of them. Either way the rules are the same short list.
Two pawns on one file (二歩 nifu)
You may not have two unpromoted pawns of your own on the same file. It is the rule a dropped pawn breaks most often, because a pawn in hand can go almost anywhere and the pawn already on the file is easy to forget. A promoted pawn (と金, tokin) moves like a gold and no longer counts as a pawn, and your opponent’s pawns never count.
The rule counts the whole file, however far apart the pawns stand. To drop another pawn there, the one on the file has to go first: exchanged, captured or promoted.
Mate by a dropped pawn (打ち歩詰め uchifuzume)
You may not drop a pawn to give checkmate. A dropped pawn may give check, and a pawn already on the board may move forward and mate; only the drop that mates is forbidden. Any other piece may be dropped for mate.
In a real game the rule works as a defence. When the only mating move is a pawn drop, the king is safe from it, and a defender can sometimes arrange exactly that position on purpose.
A piece with nowhere to go (行き所のない駒)
A piece may never stand on a square from which it could never move again. That rules out a pawn or a lance on the last rank and a knight on the last two ranks, whether it gets there by a drop or by a move that declines to promote. Moving there is fine if the piece promotes on the way, which is why a pawn reaching the last rank must promote.
The rules of promotion, and when promoting is forced, are on the promotion page.
Leaving your king in check
A move that leaves your own king attacked is illegal, whether the king walks into an attack or another piece steps out of the way of one. Tournament rules list it as 王手放置 (ōte hōchi), ignoring check, and the self-check move (自殺手, jisatsu-te). Shogi never ends in stalemate either: a player with no legal move has lost, which in practice means checkmate.
Perpetual check (連続王手の千日手)
When the same position occurs four times, the game is 千日手 (sennichite), a repetition. In professional play it is replayed with colours reversed, and online it is usually recorded as a draw. The exception is perpetual check: if one player gave check with every move of the repeating sequence, that player loses. The details, and the impasse rules, are on repetition and impasse.
The rest of the list
Tournament rules add the fouls that a board of wood allows and an app does not. Each loses on the spot in an official game:
- moving a piece in a way it cannot move;
- promoting a piece that cannot promote, or promoting on a move that neither starts nor ends in the zone;
- playing two moves in a row (二手指し, nite-sashi);
- dropping a piece you did not have in hand.
In the app
Shogi Castle refuses every illegal move, offline against the bot and online on our server, so none of these can lose you a game there. They still matter: a defender can sometimes hold on because the only mating move would be a pawn drop, and knowing the rule is how you see it.
Try the drop.
Play the bot and the app will simply not take a move these rules forbid. The lessons walk through drops and promotion one piece at a time.