The invention discloses a warning device for roads and bridges. The warning device comprises a warning plate body, a base and a connecting wire, wherein a protective plate is fixedly arranged on the outer surface of the warning plate body, a warning plate is fixedly arranged on the upper surface of the warning plate body, and a connecting column is fixedly arranged at the bottom end of the warningplate body. A mounting hole is formed in one side of an illuminating lamp, and the illuminating lamp is fixedly connected with the warning plate body. A shielding plate is fixedly arranged at the upper end of the warning plate body, an alarm is fixedly arranged at the upper end of the shielding plate, and a storage battery is arranged on one side of a solar panel. The warning device for the roadsand bridges is provided with a dustproof plug, the protective plate and a fluorescent tube, so that the mounting hole is prevented from being blocked by dust impurities, and the warning device can also be protected to a certain extent; and at night, the warning device can be used for indicating and is suitable for different working conditions, so that a better application prospect is brought.