Holder, cutting tool, and method of producing machined product

A cutting tool, comprising:

• a holder having a rod shape, a rear end and a front end opposite the rear end, the holder comprising:
• a shank portion located at the rear end of the holder;
• and
• a head portion located closer to the front end than the shank portion;
• and
• a cutting insert comprising a cutting edge,
• wherein the head portion comprises:
• an upper jaw portion and a lower jaw portion located at the front end and facing each other in an opposed manner;
• an insert pocket located between the upper jaw portion and the lower jaw portion, the cutting insert being mounted in the insert pocket such that the cutting edge of the cutting insert projects from a first side surface of the holder in a direction orthogonal to a central axis;
• a first wall surface extending toward a second side surface of the holder, opposite the first side surface, from an end portion of the first side surface on an upper surface of the upper jaw portion, the first wall surface inclined upward as the first wall surface extends toward the second side surface;
• a second wall surface located closer to the rear end than the first wall surface and located at the first side surface, the second wall surface inclined upward as the second wall surface extends toward the rear end;
• a third wall surface located closer to the rear end than the second wall surface and having a concave shape;
• and
• a fourth wall surface located closer to the rear end than the third wall surface, the fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface, and
• the third wall surface is concave downward from an upper end of the second wall surface, and the fourth wall surface is located above the upper end of the second wall surface.