We have investigated the relaxation process in the low molecular weight amorphous polystyrene around the glass-transition temperature (T_g) using adiabatic calorimetry, Temperature modulated differential scanning calorimetry (TMDSC), dynamic light scattering (DLS) measurements, dielectric relaxation and viscosity measurements. With the exception of the relaxation times determined from DLS measurements and adiabatic colorimetric measurements below T_g, the relaxation evaluated from each measurement Time showed the same temperature dependence on a time scale of 10^-6 to 10² s. The relaxation phenomena above T_g observed in adiabatic calorimetry, TMDSC, and dielectric relaxation measurements are consistent with the viscosity measurements of associated with the results, and these relaxation processes are due to the α-process directly related to the glass transition. The relaxation phenomena obtained using DLS correspond to processes based on simple diffusion motion. The relaxation observed in the adiabatic calorimetry below T_g is also due to the α-process, but it is measured under non-equilibrium thermodynamic conditions, suggesting a different temperature dependence from other α-process observations.