This study intended to investigate the level on airborne microbe in indoor air for new constructed building. It was divided by three different phase of building commissioning in Bandar Baru Bangi, Selangor. The first phase of the sampling was carried out after the building fully handed over from the main contractor to the building owner. Second phase of the sampling take place after the building is equipped with furniture. Phase three sampling is conducted after one month of building occupancy. Airborne microbes’ concentrations were determined by using a single stage impactor (Biosampler) as per requirement of National Institute of Occupational Safety and Health (NIOSH) method, NIOSH Manual Analytical Method MAM 0800. The total concentration of airborne bacteria and fungi were average to 641 and 38 CFU/m³ in the first phase, 133 and 117 CFU/m³ in the second phase, and 389 and 52 CFU/m³ in the third phase. These findings indicate that although a new constructed building should be having a significant background level of airborne microbe (total bacteria and total fungi). The building owner should be aware to their indoor air status to protect the occupant from the safety and health problem (risk) especially for ventilated building.