To provide a keyboard which can keep high input efficiency without impairing its portability by dividing the keyboard into left and right parts, securing the vertical spaces among the stages of keys of both left and right parts of the keyboard and housing the respective keys into these spaces when the keyboard is housed.

The keys which are arrayed in the same rows of an ordinary keyboard are divided into a left keyboard 10 and a right keyboard 11, and the vertical length of every key is halved in an open state of a display part 1. When the keyboard is housed, both keyboards 10 and 11 are shifted from each other by an extent equal to the vertical length of a key. Thus, the rows of keys are housed into the spaces among these rows with each other. When the keyboard is used, both keyboards 10 and 11 are horizontally separated from each other and installed on a main body 2 so as to set the keys in their original rows respectively. The keyboards 10 and 11 can be installed on the main body 2 in any way as long as they can be fixed to the main body 2.