There is provided a microemulsion aerosol composition whose hazards of flammability and explosion are reduced and which is one-layer type and does not require to shake a container containing the composition prior to use. A microemulsion aerosol composition containing an aerosol base solution comprising (a) an insecticidal ingredient, (b) a surfactant, (c) an aliphatic hydrocarbon having between 8 and 16 carbons, and (d) water, and (e) a liquefied petroleum gas as a propellant, wherein (b), (c) and (d) are contained in amounts of 5 to 20 vol %, 40 to 78 vol % and 15 to 53 vol %, respectively, in the aerosol base solution, and the surfactant (b) is composed of sorbitan fatty esters and polyoxyethylene polyoxypropylene alkyl ethers in a mixing ratio of 1:1 to 5:1.