Secondary organic aerosols (SOAs) are produced through chemical reactions initiated by the oxidation of volatile organic compounds (VOCs). Understanding of SOA formation mechanisms is still insufficient because multi-step reactions from a variety of VOCs are involved. In order to clarify the chemical mechanisms for SOA formation, we are investigating gas- and aerosol-phase species produced from VOC oxidation by using mass spectrometry and laser spectroscopy techniques. Here, we describe the application of mass spectrometry to SOA component analyses and recent results, including those from our group. Chemical kinetics studies of the VOC oxidation reactions in relation to SOA formation are also mentioned.