PROBLEM TO BE SOLVED: To provide a dental treatment chair in which a contour seat is made to slide in the longitudinal direction without using a gear at low cost.SOLUTION: A dental treatment chair 1 has a contour seat 2 and a turnable back rest 3 behind the contour seat, and is longitudinally slidable by the contour seat interlocked with the standing and falling of the back rest. The dental treatment chair includes: a first chassis for fixing the contour seat a second chassis disposed below the first chassis an arm member disposed between the first chassis and the second chassis, and longitudinally sliding while being interlocked with the standing and falling of the back rest and a seat link member for connecting the arm member, the first chassis and the second chassis. When the back rest falls down, the arm member moves forward and the seat link member makes the first chassis slide forward using the second chassis as a fulcrum.
