To provide an opening and closing device and adjuster which can easily adjust the opening and closing of a vertically opening and closing window.

This balancing device includes a balancing body 1 and a torque adjuster 2, and the balancing body 1 includes a torque holding body 13 and a load placing bar 12. By extracting the load placing bar 12 from the torque holding body 13 or turning the load placing bar 12, the torque holding body 13 is twisted and accumulates torque and can hold a sash at an opening or closing position. The torque adjuster 2 includes a first and second turning shafts 21 and 22. The second turning shaft 22 has a groove for receiving a screw driver at an end. By turning the second turning shaft 22 by the groove for receiving a screw driver, the torque holding body 13 can be twisted.