An observation device includes a handle having on a lower end side thereof an end portion including a tapered rod portion. The handle includes a protruding portion that protrudes outwardly from a side of the handle with respect to the tapered rod portion. The handle is formed so as to be held by a user to stick the rod portion into soil in a state that an index finger is applied on the handle from underneath and that a finger pad of a thumb presses against an upper end surface of the handle.