凹间（床之间）是日本住宅里叠席房间（和室）的一种装饰。在房间的一个角落做出一个内凹的小空间，主要由床柱、床框所构成。通常在其中会以挂轴、生花或盆景装饰。凹间和其中的摆饰是传统日本住宅内部必备的要素。凹间最早出现在安土桃山时代（14至16世纪）。一开始可能起源于禅宗僧侣用的佛坛，用来放置供奉物品，现代在日式房舍中的用途则为陈列插花与画轴，以营造茶道的氛围，或是烘托其他艺术品。。

凹间前方的座位被视为「上座」，因此正确的礼节是必须安排最重要的宾客背对凹间而坐。这样的礼仪是出于谦虚，主人不应该被认为要向宾客炫耀或展现凹间中的装饰，因此绝不可安排宾客面向凹间而坐。而凹间也是严格禁止踏入的。

Tokonoma(床の间,toko-no-ma), or simply toko, is a built-in recessed space in a Japanese style reception room, in which items for artistic appreciation are displayed. In English, tokonoma is usually called alcove. The items usually displayed in a tokonoma are calligraphic or pictorial scrolls and an arrangement of flowers. Bonsai and okimono are also sometimes displayed there, although traditionally, bonsai were considered to be too dirty for such a highly respected place. The tokonoma and its contents are essential elements of traditional Japanese interior decoration. The word 'toko' literally means "floor" or "bed"; 'ma' means "space" or "room."