A thermal spraying apparatus that is capable of effectively preventing the adhesion of spray fumes to unsprayed regions of a bore surface during arc spraying is provided. To this end, a thermal spraying apparatus 10 comprises a spray gun 6 that moves within a cylinder bore. The spray gun 6 has at one end thereof a first discharge opening (atomizing nozzle 62) that faces a direction that is orthogonal to the movement direction, has a second discharge opening (auxiliary nozzle 63) that faces a direction that is orthogonal to the nozzle 62, and has, at a predetermined region located further to the side in the movement direction of the spray gun 6 than the nozzle 62, third discharge openings (fume adhesion prevention nozzles 65) for discharging a fluid and that faces the same direction as the nozzle 62. A droplet, which forms as an arc spray wire material melts at the tip of the spray gun 6, is stretched with auxiliary air A1. By blowing atomizing air A2 onto the droplet, spray particles are formed and sprayed onto the bore surface. At the same time, fume adhesion prevention air A3 is blown towards the cylinder bore surface in synchrony with the spraying of the spray particles.