A hacksaw includes a frame having a chamber formed in a rear handle, an arm pivotally secured to the handle for tensioning a saw blade and having a rear oblong hole, a lever pivotally secured to the handle, and a tension rod pivotally secured to the lever and having a lower portion extended through the oblong hole of the arm. A latch has a block slidably received in the handle and has an orifice for slidably receiving the tension rod. A spring may bias the latch to engage with the lever, and may bias the arm away from the handle.