Diamond step (DS) exercises are associated with multiple components of postural control and, thus, have the potential to efficiently improve balance ability. This study aimed to verify whether DS exercises contribute to improving balance ability. This study included 35 healthy young people and 29 older adults. DS exercises were performed continuously for 3 min, four times a week, for 1 month. Balance ability was assessed at baseline and after 1 and 2 months; eight items in total were examined: 30 s chair stand test, functional reach test, standing on one leg with eyes closed, time required for five rounds of DS, left–right DS, Y balance test, open–close stepping test, and finger-to-floor distance. The difficulty, achievement, and lightness/enjoyment of DS exercises were measured after the first practice and 1 month after beginning the exercises as subjective evaluations. Older adults showed improvement in seven of the eight items, with the exception being the one-legged stance with closed eyes. The subjective evaluation showed a decrease in the level of difficulty of DS exercises for older adults. DS exercises may improve balance by effectively utilizing various postural control strategies. These exercises can be effective and easy to implement, given their moderate difficulty level and self-efficacy.