A state determination method for a work vehicle includes detecting a rotation speed of an engine of the work vehicle during a first predetermined time period. A maximum rotation speed and a minimum rotation speed during the first predetermined time period are obtained. A parameter representing a fuel injection amount of the engine during the first predetermined time period is obtained. A variation amount that is a difference between a maximum value of the parameter during the first predetermined time period and a minimum value of the parameter during the first predetermined time period is obtained. It is determined that the work vehicle is in an operating state when a difference between the maximum rotation speed and the minimum rotation speed exceeds a rotation speed threshold value, or the variation amount exceeds a variation amount threshold value.