The interface bonding strength between carbon nanotubes (CNTs) and the metal matrix in CNT/metal composites can be increased by depositing metal particles onto the CNT surface. However, theoretical calculations have revealed that metals having an affinity with CNTs formed bonds between the metal and carbon atoms, such that the tensile strength of the CNTs was decreased. Here, we investigated the influence of supported PtPd nanoparticles on the tensile strength of individual multi-walled CNTs (MWCNTs) in situ by scanning electron microscopy. The obtained results revealed that the average tensile strength of individual MWCNTs with deposited PtPd nanoparticles was slightly lower than that of the as-grown MWCNTs. Since X-ray photoelectron and Raman scattering spectroscopic data showed bonds between the PtPd nanoparticles and the MWCNTs, the slight decrease in the tensile strength observed for the PtPd nanoparticle-supported individual MWCNTs can be attributed to the induction of local distortions in the nanotube structure caused by the covalent bonds between the nanoparticles and the CNT basal plane.