There is provided a radio frequency (RF) signal amplifying device consuming less power and operable at a high voltage in a PA driving amplifying apparatus applicable to a PA amplifying circuit which amplifies power of an RF signal. The RF signal amplifying device includes: a balun converting an unbalanced radio frequency signal into a balanced radio frequency signal; a primary amplifier differentially amplifying the balanced radio frequency signal from the balun; and at least one secondary amplifier secondarily and differentially amplifying the balanced radio frequency signal amplified from the primary amplifier.