We propose a novel method to evaluate the accurate thermal stability factor Δ0 quickly, in 10 min for one target magnetic tunnel junction (MTJ), without magnetoresistance random access memory chip which includes CMOS devices. This method is based on the thermal disturbance between parallel state and antiparallel state at high temperature as well as the temperature dependence of material properties. Using this method, we have successfully demonstrated that Δ0 factors of 70 nm φ p-MTJ with single and double CoFeB/MgO interfaces at 24 °C are 76.1 and 178.2, respectively. The value of Δ0 of p-MTJ with double CoFeB/MgO interface is about twice as single one.