A production method of a purified resist composition, comprising: filtering a resist composition by allowing the resist composition to pass through a filtration filter provided with a polyimide resin porous membrane to obtain the purified resist composition, characterized in that: - the resist composition comprises a base component which exhibits changed solubility in an alkali developing solution under action of acid, an acid generator component and an organic solvent, wherein the base component comprises a polymeric compound having a structural unit (ap) containing a polar group and wherein the amount of the acid generator component relative to 100 parts by weight of the base component is within a range from 0.5 to 60 parts by weight; - the filtration filter has a porous structure in which adjacent spherical cells are mutually communicating to form a flow path, wherein the flow path between adjacent mutually communicating spherical cells is formed by: (i) mixing spherical fine particles with a polyimide resin to form a polyimide resin-fine particle composite membrane, (ii) subsequently removing the fine particles to form communicating pores, - the average diameter of the spherical cells is from 50 to 2,000 nm, wherein the average diameter of the spherical cells refers to an average value of the diameters of the communicating pores formed from two adjacent spherical cells, and the average spherical diameter of the spherical cells is a value obtained by measuring a diameter of the pore based on a bubble point method using a perm porometer, and - the filtration filter has a porosity of 60% to 90% by weight, wherein the porosity of the filtration filter is the ratio between the weight of the fine particles and the total weight of the resin and the fine particles used in the production of the filtration filter. filtering a resist composition by allowing the resist composition to pass through a filtration filter provided with a polyimide resin porous membrane to obtain the purified resist composition, characterized in that: - the resist composition comprises a base component which exhibits changed solubility in an alkali developing solution under action of acid, an acid generator component and an organic solvent, wherein the base component comprises a polymeric compound having a structural unit (ap) containing a polar group and wherein the amount of the acid generator component relative to 100 parts by weight of the base component is within a range from 0.5 to 60 parts by weight; - the filtration filter has a porous structure in which adjacent spherical cells are mutually communicating to form a flow path, wherein the flow path between adjacent mutually communicating spherical cells is formed by: (i) mixing spherical fine particles with a polyimide resin to form a polyimide resin-fine particle composite membrane, (ii) subsequently removing the fine particles to form communicating pores, - the average diameter of the spherical cells is from 50 to 2,000 nm, wherein the average diameter of the spherical cells refers to an average value of the diameters of the communicating pores formed from two adjacent spherical cells, and the average spherical diameter of the spherical cells is a value obtained by measuring a diameter of the pore based on a bubble point method using a perm porometer, and - the filtration filter has a porosity of 60% to 90% by weight, wherein the porosity of the filtration filter is the ratio between the weight of the fine particles and the total weight of the resin and the fine particles used in the production of the filtration filter. - the resist composition comprises a base component which exhibits changed solubility in an alkali developing solution under action of acid, an acid generator component and an organic solvent, wherein the base component comprises a polymeric compound having a structural unit (ap) containing a polar group and wherein the amount of the acid generator component relative to 100 parts by weight of the base component is within a range from 0.5 to 60 parts by weight; - the filtration filter has a porous structure in which adjacent spherical cells are mutually communicating to form a flow path, wherein the flow path between adjacent mutually communicating spherical cells is formed by: (i) mixing spherical fine particles with a polyimide resin to form a polyimide resin-fine particle composite membrane, (ii) subsequently removing the fine particles to form communicating pores, (i) mixing spherical fine particles with a polyimide resin to form a polyimide resin-fine particle composite membrane, (ii) subsequently removing the fine particles to form communicating pores, - the average diameter of the spherical cells is from 50 to 2,000 nm, wherein the average diameter of the spherical cells refers to an average value of the diameters of the communicating pores formed from two adjacent spherical cells, and the average spherical diameter of the spherical cells is a value obtained by measuring a diameter of the pore based on a bubble point method using a perm porometer, and - the filtration filter has a porosity of 60% to 90% by weight, wherein the porosity of the filtration filter is the ratio between the weight of the fine particles and the total weight of the resin and the fine particles used in the production of the filtration filter.