A printer positions the platen and print head in separate frames, and a stationary blade and movable blade in the separate frames, and aligns the two pair of elements independently from inaccuracy in alignment of the two separate frames to maintain the print quality of the printing mechanism and the cutting performance of the paper cutting mechanism. A support mechanism 50 has an installation frame 51 fixed to the cover 3, a support frame 52 for supporting a platen roller 12 and stationary blade 41, and a compression spring 53 attached to the installation frame 51 and support frame 52. The support frame 52 can move relative to the installation frame 51 pivotally around engaging pin 52c of the support frame 52, and slidably relative to the pivot of the cover 3. A positioning pin 61 and a positioning notch 62 are provided on the main frame 4 for positioning the support frame 52 to a position at which the platen roller 12 and stationary blade 41 are aligned to and positioned opposite the thermal head 11 and movable blade 32 respectively.