A working machine comprising: a boom of which one end is attached to a structural body supporting a work implement; an attachment (20, 30), from a plurality of attachments (20, 30) that are adapted to be selectably used, attached to the other end of the boom; a bell crank attached to a middle position of the boom in a longitudinal direction thereof; a tilt cylinder for driving the bell crank; a connecting link for connecting the bell crank and the attachment (20, 30); and a boom cylinder having an end pivoted to the structural body and the other end pivoted to the boom, wherein when the attachment is horizontally at a ground position, the tilt cylinder drives the bell crank on an upper end side thereof and the connecting link connects the bell crank to the attachment (20, 30) on a lower end side of the bell crank; the tilt cylinder connects the bell crank and the structural body; an angle between a first line segment connecting a pivot position on the boom and a pivot position on the connecting link of the bell crank and a second line segment connecting the pivot position on the boom and a pivot position on the tilt cylinder of the bell crank is set in a range from 0 degree to 180 degrees on the attachment (20, 30) side; the plurality of attachments (20, 30) comprises a bucket, the bucket being capable of assuming different postures at the ground position including a horizontally supporting posture and a tilted posture in which the bucket is tilted by the tilt cylinder; and a pivot position of the tilt cylinder on the structural body is lower compared to a pivot position of the boom on the structural body; characterized in that each of the attachment (20, 30) that is different from each other has a different pivot position on the connecting link relative to a pivot position on the boom as a reference point; and the angle between the first line segment and the second line segment is set to be equal to an angle at which absolute values of attachment angles of the attachment (20, 30) including the bucket that assumes different postures at the ground position are substantially equal to each other at any two positions from a ground position to a top position of the attachment (20, 30), wherein the attachment is lifted to the top position without changing the length of the tilt cylinder a boom of which one end is attached to a structural body supporting a work implement; an attachment (20, 30), from a plurality of attachments (20, 30) that are adapted to be selectably used, attached to the other end of the boom; a bell crank attached to a middle position of the boom in a longitudinal direction thereof; a tilt cylinder for driving the bell crank; a connecting link for connecting the bell crank and the attachment (20, 30); and a boom cylinder having an end pivoted to the structural body and the other end pivoted to the boom, wherein when the attachment is horizontally at a ground position, the tilt cylinder drives the bell crank on an upper end side thereof and the connecting link connects the bell crank to the attachment (20, 30) on a lower end side of the bell crank; the tilt cylinder connects the bell crank and the structural body; an angle between a first line segment connecting a pivot position on the boom and a pivot position on the connecting link of the bell crank and a second line segment connecting the pivot position on the boom and a pivot position on the tilt cylinder of the bell crank is set in a range from 0 degree to 180 degrees on the attachment (20, 30) side; the plurality of attachments (20, 30) comprises a bucket, the bucket being capable of assuming different postures at the ground position including a horizontally supporting posture and a tilted posture in which the bucket is tilted by the tilt cylinder; and a pivot position of the tilt cylinder on the structural body is lower compared to a pivot position of the boom on the structural body; characterized in that each of the attachment (20, 30) that is different from each other has a different pivot position on the connecting link relative to a pivot position on the boom as a reference point; and the angle between the first line segment and the second line segment is set to be equal to an angle at which absolute values of attachment angles of the attachment (20, 30) including the bucket that assumes different postures at the ground position are substantially equal to each other at any two positions from a ground position to a top position of the attachment (20, 30), wherein the attachment is lifted to the top position without changing the length of the tilt cylinder