An angle adjusting device for a bicycle saddle is disclosed. The device includes a frame coupling block, which is coupled at a lower end thereof to an upper portion of a height adjustment unit. A saddle coupling post is coupled at a lower end thereof to an upper end of the frame coupling block and is coupled at an upper end thereof to the saddle, with a through hole formed in the upper portion of the saddle coupling post. An angle fixing unit includes a pair of fan-shaped plates attached to left and right sides of the frame coupling block, and a pair of rectangular plates coupling front and rear edges of the fan-shaped plates to each other. An angle adjusting unit is coupled to the saddle coupling post, and is detachable from holes in the angle fixing unit to control the rotation of the saddle coupling post.