A spout assembly (10) for a liquid container including: a body (100) coupled to the container and centrally provided with a vertical passage (101), the body (100) including a cap coupling portion (106), a thread (106a) formed around the cap coupling portion (106), and a skirt engagement member (107) formed at a lower end of the cap coupling portion (106); a spout (110) slidably inserted into the vertical passage (101) of the body, the spout (110) including an elongated tube member (111) slidably inserted into the vertical passage of the body (100), a lower annular protrusion (112) protruded from the elongated tube member (111) and adapted to be selectively fitted in the annular groove (102) of the body (100), at least one through hole (112) radially perforated through the tube member (111), the through hole (113) being closed by an inner surface of the body defining the vertical passage (101) when the lower annular protrusion (112) is fitted in the annular groove (102) of the body, an annular cap engagement protrusion (114) formed at an upper end of the tube member, an upper annular protrusion (116) formed at the tube member (111) while being vertically spaced from the annular cap engagement protrusion to define an annular groove (115), and a liquid passage (117) defined in the tube member; and a cap (120) threadedly coupled to the cap coupling portion of the body (106), the cap (120) including a cap body, an annular groove (122) formed at an inner surface of a top wall of the cap body, the annular groove being engageable with the annular cap engagement protrusion (114) of the tube member (111), an annular protrusion (123) formed at an inner surface of a side wall (101) of the cap body, the annular protrusion (123) being engageable with the annular groove (115) of the tube member, and a thread formed on the inner surface of the cap body beneath the annular contact surface and adapted to be engageable with the thread of the body (100).