Driving tool

A driving tool comprising:

• a main chamber configured to store compressed air;
• a striking cylinder configured to move a striking piston in an axial direction along an up-down direction by being supplied with the compressed air from the main chamber;
• and
• a main valve portion configured to switch between supplying and not supplying the compressed air to the striking cylinder, the main valve portion including:
• a head valve configured to open and close communication between the striking cylinder and the main chamber;
• a main valve biasing portion configured to bias the head valve in a closing direction or an opening direction;
• and
• a control chamber configured to control opening and closing of the head valve by intake and exhaust of the compressed air supplied from the main chamber,
• wherein the main valve biasing portion is provided outside the control chamber.