PURPOSE: To improve an inputting operability at the time of carrying or installing a portable information processor by easily exchanging a key top unit whose stroke length is different only by a mechanical operation without considering an electric connectability.

CONSTITUTION: One independent key top unit is constituted of a key top 13, rubber spring 12, and key top impulse sliding member 11, and mechanically assembled without electric connection with a switching sheet 9 electrically connected through a main body main substrate 7 and a harness 6. A keyboard base member 8 is fixed to a case 16 with a screw. Plural key shapes 19 are arranged on the key board base member 8 so that the key top impulse sliding member 11 can be fixed so as to be bonded on the switching sheet 9. On the other hand, a hole for inserting the key shape 19 is formed on the key board impulse sliding member 11. And also, a protecting sheet 10 is overlapped on the switching sheet 9.