A liquid container comprises a container body (1) and a cap (2). The container body (1) has a circular tubular neck portion (13) with an outer peripheral surface provided with a protrusion (13a) for locking the cap (2). The cap (2) has a pair of lockable arms (24) arranged in a lateral direction and each provided with a hook portion (24a) adapted, during an operation of attaching the cap (2) to the container body (1), to be engaged with the locking protrusion (13a). Further, the cap (2) internally has a pair of first reinforcing ribs (26) each adapted to restrict a flexural displacement of a respective one of the lockable arms (24) in the lateral direction, and a pair of second reinforcing ribs (28) each connecting an inner surface of the cap and a respective one of the lockable arms (24) in a frontward-rearward direction.
