This is a single-blinded randomized placebo-controlled trial. Sixty-six participants with Parkinson's disease (PD) will be recruited from the Hong Kong PD association, a self-help group and movement disorder clinics of 3 local hospitals. Written informed consent in accordance with the Declaration of Helsinki will be obtained from all participants. Eligible participants will be randomly assigned into one of the three groups: 1-Hz, 25-Hz, and sham rTMS upon recruitment. Randomization was generated by a computer program and group assignment will be blinded to both participants and assessor. Participant will receive either 1-Hz, 25-Hz, or sham rTMS which will last for about 20 minutes followed by 30 minutes treadmill walking training for 12 sessions, 4 times per week for 3 weeks. All assessments will be conducted 1 week before intervention and 1 day after completion of intervention, after 1-month training and at 3-month post training. The sample size was calculated using G* power 3 statistical analysis software. A two-way repeated measures ANOVA design with between-subject group effect (3 levels) and within-subject effect (4 levels) determines that 20 subjects per group are required to achieve 80% power to test the interaction effect between group and time effect with a 5 % significance level and the effect size of 0.5. By assuming 10% dropout rate, 22 subjects will be required per group.