A power tool comprising: a tool; and a main body configured to activate the tool by using a prime mover; wherein the main body comprises: a first unit configured to attach the tool; a second unit rotatably coupled with the first unit and provided with a handle to be gripped by a user; a start operation member configured to be operated by the user between a start position and a stop position; a start cooperative switch disposed on a supply circuit for supplying energy to the prime mover, and configured to enable the supply circuit when the start operation member is at the start position and cut off the supply circuit when the start operation member is at the stop position; a lock operation member configured to be operated by the user between a lock position and an unlock position, and configured to prevent rotation of the second unit with respect to the first unit at the lock position and allow the rotation of the second unit with respect to the first unit at the unlock position; and a lock cooperative switch disposed on the supply circuit, and configured to enable the supply circuit when the lock operation member is at the lock position and cut off the supply circuit when the lock operation member is at the unlock position; characterized in that the power tool further comprises an interlock mechanism configured to allow the start operation member to move to the start position even when the lock operation member is at the unlock position, and prevent the lock operation member from moving to the lock position when the start operation member is at the start position. a tool; and a main body configured to activate the tool by using a prime mover; wherein the main body comprises: a first unit configured to attach the tool; a second unit rotatably coupled with the first unit and provided with a handle to be gripped by a user; a start operation member configured to be operated by the user between a start position and a stop position; a start cooperative switch disposed on a supply circuit for supplying energy to the prime mover, and configured to enable the supply circuit when the start operation member is at the start position and cut off the supply circuit when the start operation member is at the stop position; a lock operation member configured to be operated by the user between a lock position and an unlock position, and configured to prevent rotation of the second unit with respect to the first unit at the lock position and allow the rotation of the second unit with respect to the first unit at the unlock position; and a lock cooperative switch disposed on the supply circuit, and configured to enable the supply circuit when the lock operation member is at the lock position and cut off the supply circuit when the lock operation member is at the unlock position; characterized in that the power tool further comprises an interlock mechanism configured to allow the start operation member to move to the start position even when the lock operation member is at the unlock position, and prevent the lock operation member from moving to the lock position when the start operation member is at the start position. a first unit configured to attach the tool; a second unit rotatably coupled with the first unit and provided with a handle to be gripped by a user; a start operation member configured to be operated by the user between a start position and a stop position; a start cooperative switch disposed on a supply circuit for supplying energy to the prime mover, and configured to enable the supply circuit when the start operation member is at the start position and cut off the supply circuit when the start operation member is at the stop position; a lock operation member configured to be operated by the user between a lock position and an unlock position, and configured to prevent rotation of the second unit with respect to the first unit at the lock position and allow the rotation of the second unit with respect to the first unit at the unlock position; and a lock cooperative switch disposed on the supply circuit, and configured to enable the supply circuit when the lock operation member is at the lock position and cut off the supply circuit when the lock operation member is at the unlock position; characterized in that the power tool further comprises an interlock mechanism configured to allow the start operation member to move to the start position even when the lock operation member is at the unlock position, and prevent the lock operation member from moving to the lock position when the start operation member is at the start position.