A keypad device having a circuit of electrostatic discharge (ESD) protection is disclosed. The circuit has n and m numbers of column conductive lines and row conductive lines formed on the print circuit board wherein at least one column or row conductive line is connected to the ground and the others are, respectively, connected to the data input terminals and data output terminals of the keypad encoder. The intersections between the column (row) line which is grounded and the row (column) lines are designed for those keys, which are readily attacked by ESD such as the side keys.