Chain saw

A chain saw, comprising:

• a housing;
• a driving assembly mounted on the housing;
• a guide plate extending outward from the housing;
• a chain arranged on the guide plate and driven by the driving assembly;
• and
• a tension assembly for tightening the chain, wherein the tension assembly includes an operating member and a driving member driven by the operating member, the driving member cooperates with the guide plate, a driving force is applied to the operating member and the driving member is driven and the guide plate is moved to tension the chain, the driving force is configured for continuously rotating the operating member when the chain is tensioned to disengage the operating member from the driving member, and the operating member continues to move to compress the guide plate, and
• a tension device including a tension block, a guide shaft, a return spring and a pressing block, the tension device cooperates with the driving member and is driven by the driving member to tension the chain, and
• the tension block and the return spring are arranged on the guide shaft, and the guide shaft extends in a direction parallel to a moving direction of the guide plate.