For any real polynomial p(x) of even degree k. B. Shapiro propose the 12th conjecture saying that the sum of the number of real zeros of two polynomials ((k - 1)(p'(x))2 - kp(x)p''(x) and p(x)) is larger than 0. We comprehensively prove the original B.Shapiro's 12th conjecture and B.Shapiro's 12th conjecture of entire functions by showing all cases that the conjecture are true, and the case that it is not true. Mathematics Subject Classification: Primary 30C15 Secondary 30D20, 26C10
