Thermally stimulated current (TSC) measurements have been performed on undoped stretched poly(p-phenylene vinylene) (PPV). Two TSC peaks P₁ and P₂ are observed and become smaller as the stretching ratio was gradually increased. The trap depths are evaluated from the initial increasing part of each separated peak by the thermal cleaning method to be about 0.36 eV and 0.55 eV for peaks P₁ and P₂, respectively, regardless of the stretching ratio. However, the second peak P₂ is markedly suppressed on stretching. Peak P₁ is interpreted as originating from electron traps formed by impurities such as a bromine (Br₂) or sulphur trioxide (SO₃) which were not eliminated by heat treatment. In contrast peak P₂ was confirmed to be based on defects already existing in the amorphous parts of PPV since the crystallinity in PPV increases and the spin density evaluated by integration of the electron spin resonance spectra in stretched PPV decreases on increasing the stretching ratio.