Cutting tool and method for machining annular groove

A cutting tool comprising:

• a cutting chip;
• and
• a chip holder configured to hold the cutting chip, wherein
• the chip holder includes
• a body part having a height dimension larger than a width dimension, the body part including a first attachment face that intersects with a cutting feed direction, and a second attachment face that intersects with the first attachment face, the cutting feed direction is a length direction of the chip holder;
• a chip support part whose base end portion is connected to the body part and in which the cutting chip is attached to an upper end portion in a height direction of a tip end portion of the chip support part such that the cutting chip projects to one side in a width direction of the chip support part that intersects with the length direction;
• a reinforcement part provided along the height direction of the chip support part, the reinforcement part having a third attachment face arranged parallel to the first attachment face at a portion projecting from the body part;
• a cutout portion formed in an intersection of the third attachment face and the second attachment face;
• and
• a chip receiving part projecting to the one side in the width direction of the chip support part and configured to support the cutting chip projecting from the chip support part.