A microfluidic device comprising: a platform having a plurality of chambers (114, 116); at least one flow channel which connects between the chambers (114, 116); and a valve which opens or closes the flow channel, wherein the valve includes a blocking member which selectively blocks the flow channel and a pressing member installed in the blocking member to move the blocking member, and the pressing member has a structure which presses and moves the blocking member by the linear reciprocating motion in the same direction as the direction of an external force, and the valve further includes a driving unit which reversibly controls the opening and closing of the flow channel caused by the blocking member by fixing the pressing member to the position of the moved pressing member or returning to the original position, wherein the driving unit has a structure which selectively positions the pressing member to any one of the first position for blocking the flow channel or the second position for opening the flow channel, and the driving unit includes a fixing unit to fix the position of the pressing member moved to the first position or the second position by an external force, and a returning unit to move the pressing member to the second position, and wherein the fixing unit includes a housing located outside of the blocking member, in which the pressing member is installed to be movable; a push bar connected to the outer front end of the pressing member and extended to the outside of the housing, in which the external force is applied; characterized in that a first hole and a second hole are formed at a distance to the housing along the direction of movement of the pressing member, which define the first position or second position; an elastic bar installed in the push bar to be elastically deformable; and a projection protruded to the elastic bar, which is selectively hung at the first hole or the second hole. a platform having a plurality of chambers (114, 116); at least one flow channel which connects between the chambers (114, 116); and a valve which opens or closes the flow channel, wherein the valve includes a blocking member which selectively blocks the flow channel and a pressing member installed in the blocking member to move the blocking member, and the pressing member has a structure which presses and moves the blocking member by the linear reciprocating motion in the same direction as the direction of an external force, and the valve further includes a driving unit which reversibly controls the opening and closing of the flow channel caused by the blocking member by fixing the pressing member to the position of the moved pressing member or returning to the original position, wherein the driving unit has a structure which selectively positions the pressing member to any one of the first position for blocking the flow channel or the second position for opening the flow channel, and the driving unit includes a fixing unit to fix the position of the pressing member moved to the first position or the second position by an external force, and a returning unit to move the pressing member to the second position, and wherein the fixing unit includes a housing located outside of the blocking member, in which the pressing member is installed to be movable; a push bar connected to the outer front end of the pressing member and extended to the outside of the housing, in which the external force is applied; characterized in that a first hole and a second hole are formed at a distance to the housing along the direction of movement of the pressing member, which define the first position or second position; an elastic bar installed in the push bar to be elastically deformable; and a projection protruded to the elastic bar, which is selectively hung at the first hole or the second hole.