A bending machine comprising: a frame that includes a base section, and a punch-side frame section and a die-side frame section that are extended from both sides of the base section in an identical direction, respectively; a punch holder that is provided on the punch-side frame section and to which a punch is attached; a die holder that is provided on the die-side frame section and to which a die is attached; a pressing mechanism that presses the punch toward the die to bend a sheet material between the die and the punch; a first deflection detector that is provided in the pressing mechanism and detects a stroke of the punch required for bending the sheet material, characterized by: a second deflection detector that is supported by the die-side frame section and detects an actual displacement of the punch; and by a controller operable to previously store a relation between a deflection of the frame and a bending length, material and a sheet thickness of a sheet material, to calculate an actual deflection (δ) of the frame by subtracting a detection value of the second deflection detector from a detection value of the first deflection detector, to get a target deflection (δt) of the frame for bending a sheet material to be bent based on the relation stored, and to control the pressing mechanism so that the actual deflection (δ) becomes consistent with the target deflection (δt). a frame that includes a base section, and a punch-side frame section and a die-side frame section that are extended from both sides of the base section in an identical direction, respectively; a punch holder that is provided on the punch-side frame section and to which a punch is attached; a die holder that is provided on the die-side frame section and to which a die is attached; a pressing mechanism that presses the punch toward the die to bend a sheet material between the die and the punch; a first deflection detector that is provided in the pressing mechanism and detects a stroke of the punch required for bending the sheet material, characterized by: a second deflection detector that is supported by the die-side frame section and detects an actual displacement of the punch; and by a controller operable to previously store a relation between a deflection of the frame and a bending length, material and a sheet thickness of a sheet material, to calculate an actual deflection (δ) of the frame by subtracting a detection value of the second deflection detector from a detection value of the first deflection detector, to get a target deflection (δt) of the frame for bending a sheet material to be bent based on the relation stored, and to control the pressing mechanism so that the actual deflection (δ) becomes consistent with the target deflection (δt). a second deflection detector that is supported by the die-side frame section and detects an actual displacement of the punch; and by a controller operable to previously store a relation between a deflection of the frame and a bending length, material and a sheet thickness of a sheet material, to calculate an actual deflection (δ) of the frame by subtracting a detection value of the second deflection detector from a detection value of the first deflection detector, to get a target deflection (δt) of the frame for bending a sheet material to be bent based on the relation stored, and to control the pressing mechanism so that the actual deflection (δ) becomes consistent with the target deflection (δt).