An indoor unit of a ceiling embedded type, includes: a case having a suction port; a heat exchanger; a fan configured to suck indoor air via the suction port and send the indoor air thus sucked to the heat exchanger; an air guide member configured to guide the indoor air sucked into the fan, dividing an internal space of the case into a first space and a second space disposed downstream in an air flow with respect to the first space, and having a passage allowing a refrigerant to pass through from the second space to the first space; and a refrigerant sensor disposed in the passage closer to the first space than to the second space and configured to detect the refrigerant having passed the passage.