Provided is a positive photoresist composition excellent in terms of heat resistance. A radically curable compound is represented by a general formula (1) below (where R1, R2, and R3 each independently represent an alkyl group having 1 to 8 carbon atoms; m and n each independently represent an integer of 1 to 4; p represents an integer of 0 to 4; X, Y, and Z each independently represent an acryloyloxy group, a methacryloyloxy group, or a hydroxy group, and at least one of X, Y, and Z represents an acryloyloxy group or a methacryloyloxy group; and t represents 1 or 2).