Method for producing composite material

A method for producing a composite material including a step of curing a prepreg comprising a fiber reinforcement material and a resin composition containing a bismaleimide resin in an uncured state, the method comprising:

• a first heating step in which the prepreg is heated to a first temperature (T1) that is lower than a temperature at which the resin composition exhibits a minimum viscosity and held within a range of the first temperature (T1)±10° C. for 30 minutes or more to impregnate the resin composition in an uncured state into a fiber reinforcement material;
• and
• a curing step in which the prepreg heated to a third temperature (T3) that is the curing temperature of the resin composition and held at the third temperature (T3) to cure the resin composition,
• wherein the resin composition includes, as an essential component,
• an aromatic bismaleimide compound, wherein the content of the aromatic bismaleimide compound in the resin composition is from 30 to 65 weight %;
• and
• an alkenyl phenol compound and/or an alkenyl phenol ether compound, wherein the content of the alkenyl phenol compound and/or the alkenyl phenol ether compound in the resin composition is from 20 to 50 weight %,
• wherein the first temperature (T1) is 80 to 110° C., the third temperature (T3) is 160 to 205° C., and the first temperature (T1) satisfies the following formula (1):
• Tb≤T1≤Ta (1)
• where
• Ta is a temperature at which the resin composition exhibits a minimum viscosity and
• Tb is a temperature at which the resin composition exhibits the viscosity of 100 [Pa·s].