An insert bit includes a connecting component and a driving component. The connecting component includes a connecting end and a receiving end. The receiving end includes first and second receiving sections. The driving component is adapted to be inserted into the connecting component. The driving component includes first and second engaging sections. The first engaging section is tightly fit in the first receiving section such that the first engaging section includes an outer periphery including a flange that is formed after the first engaging section is forced into the first receiving section, and is extended radially outwards to abut against the first receiving section. The second engaging section is fit in the second receiving section. The second engaging section has a shape corresponding to the second receiving section.