To substantially improve operability by a key array capable of easily understanding the hierarchical image of a menu even when an electronic equipment is made multi-functional by the hierarchical menu.

For this key input device, by arranging a menu key operation part ME for selectively switching a plurality of high-order menu items and a selection key operation part SR for selectively switching a plurality of low- order menu items corresponding to the high-order menu items in the same direction and arranging a decision key operation part DE for deciding a selection menu in a direction almost orthogonal to the arranging direction o the menu key operation part ME and the selection key operation part SR, the key array is fitted to the hierarchical image.