Abstract: A mop thread-squeezing apparatus capable of compressing mop thread sufficiently without deteriorating the operability thereof, by applying a great pressing force to the mop thread. A pinion fixed to a driving shaft and a rack supporting one end of a squeezing plate are installed on each of left and right side plates of a squeezing tank. A radius of a pitch circle of the pinion at a point of contact between the pitch circle of the pinion and a pitch line of the rack becomes gradually smaller in a region corresponding to a former half time period of a lever operation and is almost constant in a region corresponding to a latter half time period of the lever operation. In the former half time period of the lever operation, a squeezing plate moves downward rapidly and thus the amount of the downward movement thereof is great, whereas in the latter half time period of the lever operation, the radius of the pitch circle becomes smaller and thus the pressing force of the squeezing plate becomes greater.