A machine tool, comprising: a coolant source; a turret that is supported rotatably about a rotational axis; a plurality of main spindles arranged on the turret, each main spindle is provided with a main spindle hole; a plurality of positioning blocks, each positioning block being provided to the turret so as to be adjacent a respective main spindle hole and comprising a first fluid outlet and a first fluid inlet in communication; a rotary joint that has: a hollow rotor provided with a plurality of second fluid outlets (18A1) and fixed to the turret; and a stator provided with a plurality of second fluid inlets (18B1) and supported inside the rotor so as to be rotatable about the rotational axis; a plurality of first pipes that each connects a respective one of the second fluid inlets (18B1) and the coolant source via a respective valve; and a plurality of second pipes that each connects a respective one of the second fluid outlets (18A1) and a respective one of the first fluid inlets; and a nozzle body (30, 50) for attaching to one of the main spindles, wherein the nozzle body (30, 50) comprises: a body; a shank that is attached to one of the main spindles; a shaft body (33, 53) that is provided in a protruding manner on the shank and rotatably supported by the body; an annular path that is provided on an outer circumference of the shaft body (33, 53); a discharge orifice (33D, 53D) that is provided at a leading end on the opposite side of the shaft body from the shank; a first path that is provided inside the shaft body, the first path providing communication between the discharge orifice (33D, 53D) and the annular path; a detent that is provided to the body; and a second path that is provided to the body and opens into the detent, the second path providing communication between the opening and the annular path, wherein the positioning block adjacent said one of the main spindles has an insertion hole into which the detent is inserted and its first fluid outlet is provided to the insertion hole. a coolant source; a turret that is supported rotatably about a rotational axis; a plurality of main spindles arranged on the turret, each main spindle is provided with a main spindle hole; a plurality of positioning blocks, each positioning block being provided to the turret so as to be adjacent a respective main spindle hole and comprising a first fluid outlet and a first fluid inlet in communication; a rotary joint that has: a hollow rotor provided with a plurality of second fluid outlets (18A1) and fixed to the turret; and a stator provided with a plurality of second fluid inlets (18B1) and supported inside the rotor so as to be rotatable about the rotational axis; a plurality of first pipes that each connects a respective one of the second fluid inlets (18B1) and the coolant source via a respective valve; and a plurality of second pipes that each connects a respective one of the second fluid outlets (18A1) and a respective one of the first fluid inlets; and a nozzle body (30, 50) for attaching to one of the main spindles, wherein the nozzle body (30, 50) comprises: a body; a shank that is attached to one of the main spindles; a shaft body (33, 53) that is provided in a protruding manner on the shank and rotatably supported by the body; an annular path that is provided on an outer circumference of the shaft body (33, 53); a discharge orifice (33D, 53D) that is provided at a leading end on the opposite side of the shaft body from the shank; a first path that is provided inside the shaft body, the first path providing communication between the discharge orifice (33D, 53D) and the annular path; a detent that is provided to the body; and a second path that is provided to the body and opens into the detent, the second path providing communication between the opening and the annular path, wherein the positioning block adjacent said one of the main spindles has an insertion hole into which the detent is inserted and its first fluid outlet is provided to the insertion hole. a body; a shank that is attached to one of the main spindles; a shaft body (33, 53) that is provided in a protruding manner on the shank and rotatably supported by the body; an annular path that is provided on an outer circumference of the shaft body (33, 53); a discharge orifice (33D, 53D) that is provided at a leading end on the opposite side of the shaft body from the shank; a first path that is provided inside the shaft body, the first path providing communication between the discharge orifice (33D, 53D) and the annular path; a detent that is provided to the body; and a second path that is provided to the body and opens into the detent, the second path providing communication between the opening and the annular path, wherein the positioning block adjacent said one of the main spindles has an insertion hole into which the detent is inserted and its first fluid outlet is provided to the insertion hole.