Quasi-static tests of spot welded and weld-bonded joints with 1.5 mm-thick SUS304 stainless steel sheets were conducted. Joint weld diameters were measured using scanning acoustic microscopy. Fatigue tests were performed to obtain the fatigue lives of two joint types subjected to different stress levels. The equations of load-life curves were obtained by nonlinear regression using a three parameter power function. Scanning electron microscopy was used to explore fatigue failure mechanisms of the joints. The results illustrate that nugget diameters of weld-bonded joints were smaller than those of spot welded joints. Their shear strength was lower, but weld-bonded joints showed a better fatigue performance than that of spot welded joints. Two fatigue failure modes were observed via testing: eyebrow failure mode and substrate fracture.