Alfred Nobel was interested in social issues and was engaged in the peace movement. (...) Perhaps his peace interest was also because his inventions were used in warfare and assassination attempts? Peace was the fifth and final prize area that Nobel mentioned in his will. 
The Nobel Peace Prize is one of the six Nobel prizes that awarded each year in the name of Alfred Nobel, the inventor of dynamite. Looks like was kind of upset that he had invented something that killed so many people, so he made up this prize to compensate for it.
It is awarded each year to someone who has made great efforts for human rights and done so peacefully.