PSQLException: syntax error on or near "user"

I have this error when using PreparedStatements to insert a User into a table in Postgresql called " user ", this action is carried out by crushing a button with the help of a PostgresHelper:

PostgresHelper client = new PostgresHelper(DbContract.HOST, DbContract.DB_NAME, DbContract.USERNAME,DbContract.PASSWORD);   

btnRegisterUser.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent var1) {
        // Register the new user in the db
        try {
            client.insertUser(new User(getAllData()));
        } catch (SQLException e) {
            System.out.println("Could't register the user");
            e.printStackTrace();
        }
        // Cleans textboxs
        cleanTextBoxs();
    }
});

The class PostgresHelper that contains the method to save the user in its respective user table:

package Controller;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import Model.User;

import java.sql.*;

public class PostgresHelper {

    private Connection conn;
    private String host;
    private String dbName;
    private String user;
    private String pass;


    private static final String INSERT_USER = "INSERT INTO user "
              + "(userid, name, surname, password, codice_fiscale) VALUES (?,?,?,?,?)";

    public PostgresHelper(String host, String dbName, String user, String pass) {
        this.host = host;
        this.dbName = dbName;
        this.user = user;
        this.pass = pass;
    }

    public boolean connect() throws SQLException, ClassNotFoundException {
        if (host.isEmpty() || dbName.isEmpty() || user.isEmpty() || pass.isEmpty()) {
            throw new SQLException("Database credentials missing");
        }

        Class.forName("org.postgresql.Driver");
        this.conn = DriverManager.getConnection(this.host + this.dbName, this.user, this.pass);
        return true;
    }

    public void insertUser(User user) throws SQLException {

        String userId = user.getUserID();
        String name = user.getName();
        String surname = user.getSurname();
        String password = user.getPassword();
        String codiceFiscale = user.getCodiceFiscale();

        PreparedStatement pstmt = conn.prepareStatement(INSERT_USER);

        pstmt.setString(1, userId);
        pstmt.setString(2, name);
        pstmt.setString(3, surname);
        pstmt.setString(4, password);
        pstmt.setString(5, codiceFiscale);
        pstmt.executeQuery();

        System.out.println("User registered");
    }

}