A ceiling installation type air conditioner comprising: a blower chamber including an air inlet; a heat exchange chamber including an air outlet; a partition plate separating the blower chamber and the heat exchange chamber from each other; a blower accommodated in the blower chamber; and a heat exchanger accommodated in the heat exchange chamber, wherein the blower chamber is spatially connected with the heat exchange chamber via the blower; wherein the heat exchanger includes a first heat exchange section, a second heat exchange section, and a third heat exchange section; wherein each of the first heat exchange section, the second heat exchange section, and the third heat exchange section includes a plurality of plate-shaped fins and a plurality of heat transfer tubes; and wherein the first heat exchange section, the second heat exchange section, and the third heat exchange section are disposed in a convex shape as a whole toward the air outlet, wherein the first heat exchange section is inclined in such a manner that an upper end portion of the first heat exchange section is positioned on a windward side of a lower end portion of the first heat exchange section, wherein the second heat exchange section is positioned at the upper portion of the heat exchange chamber and is disposed such that a front end portion of the second heat exchange section and an upper end portion of the first heat exchange section are continuous, wherein a front end portion of the third heat exchange section protrudes more towards the air outlet than the lower end of the first heat exchange section, wherein a shape of the plurality of plate-shaped fins of the first heat exchange section is line-symmetrical with a shape of the plurality of plate-shaped fins of the third heat exchange section, and in the second heat exchange section, the length dimension of a long side of each of the fins is shorter than that of the other heat exchange sections. a blower chamber including an air inlet; a heat exchange chamber including an air outlet; a partition plate separating the blower chamber and the heat exchange chamber from each other; a blower accommodated in the blower chamber; and a heat exchanger accommodated in the heat exchange chamber, wherein the blower chamber is spatially connected with the heat exchange chamber via the blower; wherein the heat exchanger includes a first heat exchange section, a second heat exchange section, and a third heat exchange section; wherein each of the first heat exchange section, the second heat exchange section, and the third heat exchange section includes a plurality of plate-shaped fins and a plurality of heat transfer tubes; and wherein the first heat exchange section, the second heat exchange section, and the third heat exchange section are disposed in a convex shape as a whole toward the air outlet, wherein the first heat exchange section is inclined in such a manner that an upper end portion of the first heat exchange section is positioned on a windward side of a lower end portion of the first heat exchange section, wherein the second heat exchange section is positioned at the upper portion of the heat exchange chamber and is disposed such that a front end portion of the second heat exchange section and an upper end portion of the first heat exchange section are continuous, wherein a front end portion of the third heat exchange section protrudes more towards the air outlet than the lower end of the first heat exchange section, wherein a shape of the plurality of plate-shaped fins of the first heat exchange section is line-symmetrical with a shape of the plurality of plate-shaped fins of the third heat exchange section, and in the second heat exchange section, the length dimension of a long side of each of the fins is shorter than that of the other heat exchange sections.