We prove the total positivity of the Narayana triangles of type A and type B, and thus affirmatively confirm a conjecture of Chen, Liang and Wang and a conjecture of Pan and Zeng. We also prove the strict total positivity of the Narayana squares of type A and type B.Keywords: Totally positive matrices, the Narayana triangle of type A, the Narayana triangle of type B, the Narayana square of type A, the Narayana square of type B