A slide rail (10) by which a conveyance seat is coupled to a floor in a slidable state with respect to the floor includes: a lower rail (11) attached on the floor; an upper rail (12) slidably assembled to the lower rail (11) and attached to the conveyance seat; and a locking spring (13A) installed on the upper rail (12) and having a locking piece that is inserted into a locking slit (11B1) formed in the lower rail (11) to prohibit the upper rail (11) and the lower rail (12) from sliding relative to each other. The locking spring (13A) has the following structure that the locking piece extends in a direction along a cross-section (the width direction) of the upper rail (12) from a position in the locking spring, at which the locking spring is supported by the upper rail (12). The locking piece is inserted into the locking slit (11B1) by deflection deformation of the locking piece in an in-plane direction of the cross-section (the height direction) of the upper rail (12).