A bipolar junction transistor (BJT) device includes a semiconductor substrate, a first doping region with a first conductivity, a second doping region with a second conductivity, a third doping region with the first conductivity, at least one stacked block and a conductive contact. The first doping region is formed in the semiconductor substrate. The second doping region is formed in the first doping region. The at least one stacked block is formed on and insulated from the second doping region. The third doping region is formed in the second doping region and disposed adjacent to the at least one stacked block. The conductive contact electrically connects the at least one stacked block with the third doping region.