It looks like a nyckelharpa, also known as a keyed fiddle.

Max Wade Matthew's Encylopedia of musical instruments states that these were used throughout Scandavia for popular dance, festive and folk music. 15th century nyckelharpan had between 7 and 12 wooden keys and from 3 to 6 strings, some of which were drones. The oldest surviving nyckelharpan date from the 16th century and are of 2 types. One has an elongated body in the shape of a figure eight, with a flat bottom and flat soundboard. The second type is pear-shaped and the soundboard and neck are made in a single piece. More recently the shape of this type has come to resemble that of the violin family.

A 19th century watercolour by Per Nordquist shows a man playing one, he has it strung over his shoulder similar to a guitar but slanted almost flat like a dobro, the left hand is working the frets while the right hand is bowing