The incident took place around 7.40am this morning at a bus stop between Drovers Road and Little Sheil Road.
The suspect is described as white, of slim build, 5ft 9-10ins tall, in his thirties, with short dark receding hair, distinctive side burns and dark stubble.
He was wearing a high-vis short-sleeved t-shirt with a dark panel on the back, high-vis trousers and trainers.
He was last seen heading in the direction of Main Street, possibly into Almondell & Calderwood Country Park.
PC Nichola McConnell of Broxburn Police Station said: “This was a very distressing incident for the woman and we’re urging anyone who may have seen the man in the area, or who recognises his description, to contact us as soon as possible. There has been an increase in patrols in the area since this incident was reported and this will continue over the coming days.”
Anyone with information is asked to contact Police Scotland on 101, quoting incident number 0609 of 10 June, or report this anonymously to Crimestoppers on 0800 555 111.