The present invention is to provide a new surfactant that can be used as an emulsifier excellent in emulsion stability and texture in use and as a cleanser excellent in cleansing power and texture in use and having low skin irritation. A surfactant consisting of a compound represented by the below-described general formula (1). Y—O-(EO)l-(AO)m-(EO)n-X  (1) (In the formula, AO represents an oxyalkylene group having 3 to 4 carbon atoms; m is the average addition mole number of the oxyalkylene group and satisfies 5≦m≦100. EO represents an oxyethylene group; l and n are the average addition mole numbers of the oxyethylene groups and satisfy 0≦l≦4 and 0≦n≦4. Either X or Y or both are a functional group represented by —SO3M, —COOM, —HPO3M, —(CH2)q—SO3M, or —(CH2)q—COO, wherein M is a hydrogen ion or a monovalent inorganic or organic cation, and q is the number of carbon atoms of the linked alkylene group and satisfies 1≦q≦4. When either X or Y is the above-described functional group, the other one can be a hydrogen atom, a methyl group, or an ethyl group.)