Spring-incorporated mattress capable of being deformed in rolled state

The present invention is a spring-incorporated mattress (10) including : a spring structure (1) including a spring coil; a frame (2) made of an elastic material and arranged at least on a front side and a rear side or on a right side and a left side of the spring structure (1); an upper-side extensible member (3) arranged on an upper side of the spring structure (1) and the frame (2); and a lower-side extensible member (4) arranged on a lower side of the spring structure (1) and the frame (2). Each of the upper-side extensible member (3) and the lower-side extensible member (4) consists of compressed synthetic-resin cotton whose thickness is not less than 0.5 cm and whose weight is within a range of 300g to 600g, or a hard felt whose thickness is not less than 0.5 cm and whose weight is within a range of 300g to 600g, so that the spring-incorporated mattress is capable of being deformed in a rolled state and capable of being returned to an original flat state when released from the rolled state.