To provide a simple dental impression material kneading device capable of obtaining a dental impression material in an excellent condition with the ratio of mixture of two kinds of pastes, whose fluidity is different at the time of start of spouting from containers, within a prescribed range from the initial stage of mixing/kneading.

The dental impression material kneading device comprises a cylindrical mixer body M, an outer casing S detachably set in the outer peripheral surface of the mixer body M, and a mixer body mounting part 2 with a rotating shaft 2a on the center axis, projecting to be inserted into/engaged with an agitation rod K of the mixer body M for mixing/kneading the pastes. Two kinds of pastes stored in a pair of containers with different fluidity at the start of spouting from the containers are fed out from a pair of inlets 1x and 1y, to which the pastes are supplied respectively, to a pair of outlets 3x and 3y formed in the mixer body mounting part 2. The dental impression material kneading device also has a reservoir part 5 disposed in a region where one outlet 3x of the mixer body mounting part 2 is formed in such a way as to form a recess on the inlet side from the face where the other outlet 3y is formed, for reserving a prescribed quantity of the paste whose fluidity is higher at the time of start of spouting from the container through the outlet 3x.