The acute and chronic effects of static stretching (SS) on joint range of motion (ROM) and stiffness of muscle-tendon unit (MTU) and/or muscle was reviewed. Previous studies have provided evidence that SS is effective in increasing ROM, both immediately and chronically. Moreover, 75 seconds (75s) SS is sufficient for eliciting an immediate, acute effect. In contrast, the recent trend is to evaluate the effect of stretching not by measuring ROM, but by measuring stiffness in order to eliminate the effect of psychological factors. However, the findings of studies measuring stiffness are conflicting, with some results indicating a decrease in stiffness and others indicating no change in stiffness despite changes in joint ROM. Our study results support that stiffness decrease with SS, and that >2 min of SS is effective in eliciting the effect. The retention time taken to achieve the effect of SS is also under discussion, and the retention time may differ for ROM and muscle stiffness. Concerning the chronic effect of SS, many studies have indicated that a routine SS program decreases passive torque or MTU and muscle stiffness. However, the underlying mechanism for this decrease remains to be clarified.