Wang died on the spot due to explosion while injuring eight others, including three seriously who were later sent to hospital.
Wang used to work as a webmaster in the company until March 2012 over a wage dispute and went there yesterday carrying a bag of home-made explosives to demand compensation, state-run Xinhua news agency quoted police as saying.
He later ignited explosives beside the elevator after being pushed out of the office, killing himself on the spot, police said.
Injured are stated to be in stable conditions.