A terminal comprising: a terminal main body having an electrical conductivity, and including a contact portion; and an insulation member including a terminal holding portion arranged on a rear end side of the contact portion and adapted to be held in a housing, wherein the terminal holding portion includes a rotation prevention portion adapted to be located between and sandwiched by a pair of locking portions formed in the housing to prevent rotation of the terminal in the housing, the pair of the locking portion including arm portions and a locking claw portions formed at distal ends of the arm portions, and the rotation prevention portion includes: a first engaged portion adapted to be engaged with the locking claw portions in a state while the terminal is being installed along an extension direction of the center axis of the terminal into the housing, and a second engaged portion adapted to be engaged with the locking claw portions when installing of the terminal into the housing is finished, and adapted to prevent detachment of the terminal from the housing, the first engaged portion includes a pair of first planar portions being parallel to each other, and the second engaged portion includes a pair of second planar portions being parallel to the pair of the first planar portions, whereby a value of a distance between the pair of second planar portions is smaller than a value of a distance between the pair of first planar portions. a terminal main body having an electrical conductivity, and including a contact portion; and an insulation member including a terminal holding portion arranged on a rear end side of the contact portion and adapted to be held in a housing, wherein the terminal holding portion includes a rotation prevention portion adapted to be located between and sandwiched by a pair of locking portions formed in the housing to prevent rotation of the terminal in the housing, the pair of the locking portion including arm portions and a locking claw portions formed at distal ends of the arm portions, and the rotation prevention portion includes: a first engaged portion adapted to be engaged with the locking claw portions in a state while the terminal is being installed along an extension direction of the center axis of the terminal into the housing, and a second engaged portion adapted to be engaged with the locking claw portions when installing of the terminal into the housing is finished, and adapted to prevent detachment of the terminal from the housing, the first engaged portion includes a pair of first planar portions being parallel to each other, and the second engaged portion includes a pair of second planar portions being parallel to the pair of the first planar portions, whereby a value of a distance between the pair of second planar portions is smaller than a value of a distance between the pair of first planar portions. a first engaged portion adapted to be engaged with the locking claw portions in a state while the terminal is being installed along an extension direction of the center axis of the terminal into the housing, and a second engaged portion adapted to be engaged with the locking claw portions when installing of the terminal into the housing is finished, and adapted to prevent detachment of the terminal from the housing, the first engaged portion includes a pair of first planar portions being parallel to each other, and the second engaged portion includes a pair of second planar portions being parallel to the pair of the first planar portions, whereby a value of a distance between the pair of second planar portions is smaller than a value of a distance between the pair of first planar portions.