A pitch adjusting mechanism for a bicycle saddle is arranged between a saddle and a seat post of the bicycle and includes: a base beneath the saddle; a connecting member being fixed to the seat post; a washer being removably assembled to a top or a bottom of the connecting member; and a fastener combining the connecting member, the washer and the base as a whole. When the washer is arranged on the top and beneath the bottom of the connecting member, a pitch of the saddle with respect to the seat post is different.