A method of producing arabitol by continuous fermentation of at least one sugar by micro-organisms producing arabitol, characterised in that arabitol is produced in a first fermentation area including at least one fermenter in such a manner that some of the sugar introduced into the fermentation medium is consumed by said micro-organisms, some of the fermentation medium obtained in this way is transferred into a second fermentation area including at least one fermenter, the volume being maintained constant in the first fermentation area by adding sugar, production of arabitol continues in said second fermentation area in such a manner as to consume the residual sugar of the fermentation medium, the fermentation medium thus obtained from said second fermentation area is separated a continuously into a fraction concentrated in micro-organisms and another, soluble fraction enriched in arabitol, and the arabitol thus obtained is collected.