Bit replacing device for excavating machine

A bit replacing device for an excavating machine, the bit replacing device being provided on a cutter head which is placed in a front part of an excavating machine body to excavate ground, the bit replacing device comprising:

• a rear surface frame provided on a rear surface side of a front surface plate of the cutter head to form a workspace for an operator to enter and exit;
• an opening into and from which at least one replacement bit can be inserted and removed, the opening being formed on the front surface plate;
• a bit guide body provided on a rear surface side of the opening, the bit guide body having a bit guide hole through which the replacement bit can be inserted and fixed;
• a gate plate placed between the front surface plate and the bit guide body so as to turn about an opening/closing axial center normal to the front surface plate, the gate plate having a valve port through which the replacement bit can be inserted and removed;
• and
• a gate opening/closing device capable of turning the gate plate between a communication position for communicating the opening with the bit guide hole and a closed position where the opening is closed.