To provide an integrated-separation type sheet material cutting device capable of smoothly integrating a fixed blade with a rotary blade without causing any mechanical collision, and a printer with the same mounted thereon.

In the integrated-separation type sheet material cutting device, a fixed blade having a cutting edge extending in the cutting width direction, and a rotary blade having a cutting edge extending in the cutting width direction are arranged in an integrating-separating manner, and when the fixed blade and the rotary blade area pressed against each other by integration with the shear angle, and engaged with each other to cut a sheet. The fixed blade is moved on a track not to be interfered with the rotary blade, and brought close to the predetermined position to the rotary blade. Then, the fixed blade is moved toward the rotary blade, and brought into contact with the rotary blade from a plate surface side having the cutting edge of the fixed blade, and the fixed blade is integrated with the rotary blade.