An underfill material having sufficient curing reactivity, and capable of achieving a small change in viscosity and good electrical connection even when loaded with thermal history, a laminated sheet including the underfill material, and a method for manufacturing a semiconductor device. The underfill material has a melt viscosity at 150° C. before heating treatment of 50 Pa·s or more and 3,000 Pa·s or less, a viscosity change rate of 500% or less, at 150° C. as a result of the heating treatment, and a reaction rate represented by {(Qt−Qh)/Qt}×100% of 90% or more, where Qt is a total calorific value in a process of temperature rise from −50° C. to 300° C. and Qh is a total calorific value in a process of temperature rise from −50° C. to 300° C. after heating at 175° C. for 2 hours in a DSC measurement.