Medical instrument and adjustment method of medical instrument

A medical instrument comprising:

• an instrument unit comprising:
• an end effector fulfilling a predetermined function;
• and
• a wire;
• an adapter comprising:
• a motor for generating power to drive the end effector;
• and
• a fixing portion;
• and
• a tension holding portion comprising:
• a pulley movable in translation along a direction and with which the wire comes into contact;
• and
• a spring for biasing the pulley;
• wherein the tension holding portion being configured to maintain a tension applied to the wire at a predetermined magnitude due to a movement of the pulley in the direction;
• the wire is connected to both the end effector and the motor so as to transmit the power generated by the motor to the end effector;
• the fixing portion is configured to fix a position of the pulley;
• and
• when the instrument unit is mounted on the adapter, the motor and the wire are connected with each other while the pulley is fixed by the fixing portion so as to be immovable in the direction.