An iPod Touch was taken from a car in the Tesco car park in Lerwick yesterday afternoon.
It was taken between 1.20pm and 2.20pm, police say.
It comes after police issued a warning over a spate of sneak-in thefts in the town last week. The force has urged motorists to lock their doors.
Anyone with information should contact Lerwick police station: 01595 692110.