The present invention provides a sewing machine that can actuary detect a physical amount of a movement of a fabric without depending on an estimated value. Thus, thread tension can be precisely adjusted. A sewing machine 1 includes a spherical body 22a exposed partly from a needle plate 2. The spherical body 22a is rotated following a feed of a fabric 100. The rotation of the spherical body 22a is detected by rotary encoders 22c, 22d. A physical amount of the movement of the fabric 100 is calculated based on a detection result of the rotary encoders 22c, 22d. The physical amount of the movement of the fabric 100 is, for example, a moving amount and a moving speed.

A sewing machine moves a needle up and down relative to a cloth based on drive force from a rotating upper shaft to form a stitch. A first output generating unit reciprocates a first output point along an output axis so as to convert the rotational motion of the upper shaft into a linear motion. An assist rod that serves as a connection portion links the first output point with a needle bar. A needle-bar swing unit swings the needle bar. An output shaft moving unit moves a guide that is the output axis in a cloth feeding direction in accordance with the motion of the needle-bar swing unit. The assist rod changes the inclination in accordance with the movement of the output axis, and reciprocates the needle bar in substantially parallel with the output axis while maintaining the inclination.

The present invention provides a sewing machine that can actuary detect a physical amount of a movement of a fabric without depending on an estimated value. Thus, thread tension can be precisely adjusted. A sewing machine 1 includes a spherical body 22a exposed partly from a needle plate 2. The spherical body 22a is rotated following a feed of a fabric 100. The rotation of the spherical body 22a is detected by rotary encoders 22c, 22d. A physical amount of the movement of the fabric 100 is calculated based on a detection result of the rotary encoders 22c, 22d. The physical amount of the movement of the fabric 100 is, for example, a moving amount and a moving speed.