An air conditioner comprising: a housing forming an air inlet and an air outlet disposed below the air inlet ; a heat exchanger for exchanging heat with a outside air introduced into the housing through the air inlet ; a blowing fan disposed inside the housing and in an upper rear side of the air outlet , and rotatable about a rotational axis formed in a left-right direction so that air suctioned through the air inlet flows toward the air outlet ; a lower guide guiding air, discharged to a rear side and a lower side of the blowing fan , toward the air outlet ; and an upper guide disposed above the lower guide to form a discharge flow path with the lower guide in such a way that a cross section of the discharge flow path from the blowing fan to the air outlet is extended gradually toward the air outlet , wherein the upper guide forms a curved surface at an end adjacent to the air outlet , the surface which is convex in a direction toward the air outlet , characterized in that : the upper guide comprises a plurality of protrusions formed at an upstream side of the upper guide to vertically protrude from a surface formed by the upper guide , and spaced apart from each other in a rotational axis direction of the blowing fan , and the upper guide is formed with a plurality of grooves elongated in a direction in which air flows along the discharge flow path , and recessed inwardly of the upper guide . a housing forming an air inlet and an air outlet disposed below the air inlet ; a heat exchanger for exchanging heat with a outside air introduced into the housing through the air inlet ; a blowing fan disposed inside the housing and in an upper rear side of the air outlet , and rotatable about a rotational axis formed in a left-right direction so that air suctioned through the air inlet flows toward the air outlet ; a lower guide guiding air, discharged to a rear side and a lower side of the blowing fan , toward the air outlet ; and an upper guide disposed above the lower guide to form a discharge flow path with the lower guide in such a way that a cross section of the discharge flow path from the blowing fan to the air outlet is extended gradually toward the air outlet , wherein the upper guide forms a curved surface at an end adjacent to the air outlet , the surface which is convex in a direction toward the air outlet , characterized in that : the upper guide comprises a plurality of protrusions formed at an upstream side of the upper guide to vertically protrude from a surface formed by the upper guide , and spaced apart from each other in a rotational axis direction of the blowing fan , and the upper guide is formed with a plurality of grooves elongated in a direction in which air flows along the discharge flow path , and recessed inwardly of the upper guide . the upper guide comprises a plurality of protrusions formed at an upstream side of the upper guide to vertically protrude from a surface formed by the upper guide , and spaced apart from each other in a rotational axis direction of the blowing fan , and the upper guide is formed with a plurality of grooves elongated in a direction in which air flows along the discharge flow path , and recessed inwardly of the upper guide . <EOS>