Abstract: A safety device (2) for use in safely restraining an infant, particularly on a flat substrate, is described, the safety device (2) comprising a support portion (4) for supporting the body of the infant and a harness portion (20) for restraining the body of the infant in the supported position in which the harness (20) includes a number of flaps (16, 22, 24, 28) which co-operate with each other to envelop a part of the body of the infant, thereby restraining the infant. The device may be in the form of a U-pillow or in the form of a pillowcase for a U-pillow. In addition, the device is provided with a pocket (14) for storing the harness when not in use and for acting as a neck, head or shoulder rest by providing an extra thickness of padding.