Abstract: A cap crown button comprises a female retaining body, a male retaining body and a covering body. The female retaining body is provided with a retaining hole having at the upper end thereof a receiving space in which a connection portion, a receiving portion and a tapered portion are disposed. When the pin column of the male retaining body is inserted into the retaining hole of the female retaining body, the tapered head of the pin column of the male retaining body is rested against the tapered portion such that the bottom edge of the tapered head of the male retaining body is received in the receiving portion of the retaining hole. The retaining effect of the male retaining body and the female retaining body is therefore effectively enhanced without causing the tapered head of the male retaining body to pierce through the female retaining body.