A thermal treatment apparatus includes a fluidic device including at least one channel, a first temperature-changing unit that changes the temperature of a fluid in part of the channel, and a second temperature-changing unit that changes the temperature of the fluid in another part of the channel. The temperature changes by the first and second temperature-changing units cause at least any one of the expansion and contraction of the fluid in the respective parts of the channel, and the at least any one of the expansion and contraction of the fluid due to the first temperature-changing unit is offset by the at least any one of the expansion and contraction of the fluid due to the second temperature-changing unit.