1. A digital signage comprising:a housing including a closed inner space;
a cooling unit provided in a top portion of the housing, the cooling unit including at least one hole configured to suck and exhaust external air;
a display panel arranged in one surface of the housing,
a heat pipe including one end positioned in the inner space of the housing to be coupled to a back surface of the display panel and another end positioned in the cooling unit, with a liquid flowing therein to move heat; and
a driving circuit board coupled to a back surface of the heat pipe to control operating of the display panel,
wherein a horizontal cross section of the heat pipe has a rectangular shape having two long sides and two short sides, and wherein one long side of the two long sides directly contacts with the display panel, another long side of the two long sides directly contacts with the driving circuit board, and the two short sides of the heat pipe are perpendicular to the display panel.