A prediction device that predicts time for a reducing agent accommodated in a container mounted on a work vehicle to freeze includes a remaining amount information acquisition unit configured to acquire remaining amount information indicating a remaining amount of the reducing agent in the container, a wall surface temperature acquisition unit configured to acquire a detection result of a wall surface temperature of the container, a reducing agent temperature acquisition unit configured to acquire a detection result of a temperature of the reducing agent, and a time calculation unit configured to calculate the time for the reducing agent to freeze based on the wall surface temperature, the reducing agent temperature, and the remaining amount information.