Handheld printer

A handheld printer comprising:na platen roller configured to feed said print-receiving paper;a thermal line head configured to perform desired printing on said print-receiving paper fed by said platen roller;a pair of side chassis members configured to support said platen roller in a rotatable manner and support said thermal line head so that said thermal line head can press against said platen roller;a housing comprising a top cover constituting a device contour upper part and an undercover constituting a device contour lower part; anda chassis assembly comprising said pair of side chassis members, wherein:said housing encloses said chassis assembly;said chassis assembly further comprises an installation part where a screw hole is formed;said top cover comprises a first boss part provided protruding toward the device inside;said undercover comprises a second boss part provided protruding toward the device inside to a position corresponding to said first boss part of said top cover;said chassis assembly, said top cover, and said undercover are assembled to each other by inserting a screw inserted from one of said first boss part and said second boss part through said screw hole of said installation part and connecting said screw to the other said boss part; anda buffering member is provided between at least one of said first boss part and said second boss part and said installation part.