A pedal device for playing a drum has a base, two posts, a shaft, an arm, a drumstick, a pedal, a spring, a sling hook and a connection member. The posts are mounted on the base. The shaft is mounted rotatably between the post and has two ends. The arm is mounted on one end of the shaft. The drumstick is attached securely to and perpendicularly extends out from the shaft. The sling hook hooks on arm. The connection member is mounted on the base. A diameter of the spring gradually is shortened at two ends of the spring, which forms two mounting portions. Each of the sling hook and the connection member has a knob formed thereon. The knobs are coaxially embedded respectively in the mounting portions of the spring. A pulling force on the spring distributed uniformly, so the pedal device can be treaded smoothly.