PURPOSE: To obtain monofilament for fishing net, having excellent heat stability of melt during spinning and slight reduction in strength caused by wet heat treatment, comprising a polyamide resin wherein the number of end carboxyl groups and the number of end amino groups satisfy a specific condition.

CONSTITUTION: A diamine (e.g. hexamethylenediamine) and a dicarboxylic acid (e.g. adipic acid) are fed to an autoclave, sealed in a nitrogen atmosphere, heated to 260°C, reacted while stirring for two hours under pressure and the polyamide resin is drawn into strand and pelletized. 100 pts.wt. of the polyamide resin is blended with 0.01-1 pt.wt. ethylene bisstearoamide, subjected to melt spinning by using both an extruder and a die at 240-260°C and drawn to give the objective monofilament comprising the polyamide wherein the number [A] (μeq/1g polymer) of end carboxyl groups and the number [B] (μeq/1g polymer) of end amino groups satisfy [B]>([A]+5).