diff --git a/process/process_darwin.go b/process/process_darwin.go
index d4c0e2e..5b1f1bd 100644
--- a/process/process_darwin.go
+++ b/process/process_darwin.go
@@ -4,6 +4,7 @@ package process
 
 import (
 	"bytes"
+	"fmt"
 	"strconv"
 	"strings"
 	"syscall"
@@ -92,7 +93,18 @@ func (p *Process) Cwd() (string, error) {
 	return "", common.NotImplementedError
 }
 func (p *Process) Parent() (*Process, error) {
-	return p, common.NotImplementedError
+	r, err := callLsof("R", p.Pid)
+	if err != nil {
+		return nil, err
+	}
+	if len(r) != 1 { // TODO: pid 1
+		return nil, fmt.Errorf("wrong number of parents")
+	}
+	v, err := strconv.Atoi(r[0])
+	if err != nil {
+		return nil, err
+	}
+	return NewProcess(int32(v))
 }
 func (p *Process) Status() (string, error) {
 	r, err := callPs("state", p.Pid, false)
@@ -166,15 +178,6 @@ func (p *Process) NumFDs() (int32, error) {
 	return 0, common.NotImplementedError
 }
 func (p *Process) NumThreads() (int32, error) {
-	/*
-		k, err := p.getKProc()
-		if err != nil {
-			return 0, err
-		}
-
-			return k.KiNumthreads, nil
-	*/
-
 	r, err := callPs("utime,stime", p.Pid, true)
 	if err != nil {
 		return 0, err
@@ -412,3 +415,26 @@ func callPs(arg string, pid int32, threadOption bool) ([][]string, error) {
 
 	return ret, nil
 }
+
+func callLsof(arg string, pid int32) ([]string, error) {
+	var cmd []string
+	if pid == 0 { // will get from all processes.
+		cmd = []string{"-F" + arg}
+	} else {
+		cmd = []string{"-a", "-F" + arg, "-p", strconv.Itoa(int(pid))}
+	}
+	out, err := invoke.Command("/usr/sbin/lsof", cmd...)
+	if err != nil {
+		return []string{}, err
+	}
+	lines := strings.Split(string(out), "\n")
+
+	var ret []string
+	for _, l := range lines[1:] {
+		if strings.HasPrefix(l, arg) {
+			ret = append(ret, l[1:]) // delete first char
+		}
+	}
+
+	return ret, nil
+}
diff --git a/process/process_linux.go b/process/process_linux.go
index 9c145e6..79039bf 100644
--- a/process/process_linux.go
+++ b/process/process_linux.go
@@ -4,6 +4,7 @@ package process
 
 import (
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -11,10 +12,10 @@ import (
 	"strings"
 	"syscall"
 
-	common "github.com/shirou/gopsutil/common"
-	cpu "github.com/shirou/gopsutil/cpu"
-	host "github.com/shirou/gopsutil/host"
-	net "github.com/shirou/gopsutil/net"
+	"github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/cpu"
+	"github.com/shirou/gopsutil/host"
+	"github.com/shirou/gopsutil/net"
 )
 
 const (
@@ -94,7 +95,18 @@ func (p *Process) Cwd() (string, error) {
 	return p.fillFromCwd()
 }
 func (p *Process) Parent() (*Process, error) {
-	return nil, common.NotImplementedError
+	r, err := callLsof("R", p.Pid)
+	if err != nil {
+		return nil, err
+	}
+	if len(r) != 1 { // TODO: pid 1
+		return nil, fmt.Errorf("wrong number of parents")
+	}
+	v, err := strconv.Atoi(r[0])
+	if err != nil {
+		return nil, err
+	}
+	return NewProcess(int32(v))
 }
 func (p *Process) Status() (string, error) {
 	err := p.fillFromStatus()
@@ -619,3 +631,26 @@ func Pids() ([]int32, error) {
 
 	return ret, nil
 }
+
+func callLsof(arg string, pid int32) ([]string, error) {
+	var cmd []string
+	if pid == 0 { // will get from all processes.
+		cmd = []string{"-F" + arg}
+	} else {
+		cmd = []string{"-a", "-F" + arg, "-p", strconv.Itoa(int(pid))}
+	}
+	out, err := invoke.Command("/usr/bin/lsof", cmd...)
+	if err != nil {
+		return []string{}, err
+	}
+	lines := strings.Split(string(out), "\n")
+
+	var ret []string
+	for _, l := range lines[1:] {
+		if strings.HasPrefix(l, arg) {
+			ret = append(ret, l[1:]) // delete first char
+		}
+	}
+
+	return ret, nil
+}
diff --git a/process/process_test.go b/process/process_test.go
index 84d311b..2d2c9c5 100644
--- a/process/process_test.go
+++ b/process/process_test.go
@@ -1,7 +1,6 @@
 package process
 
 import (
-	"fmt"
 	"os"
 	"runtime"
 	"strings"
@@ -38,7 +37,7 @@ func Test_Pids_Fail(t *testing.T) {
 	mu.Lock()
 	defer mu.Unlock()
 
-	invoke = common.FakeInvoke{Suffix: "fail", Error: fmt.Errorf("hoge")}
+	invoke = common.FakeInvoke{Suffix: "fail"}
 	ret, err := Pids()
 	invoke = common.Invoke{}
 	if err != nil {
@@ -48,7 +47,6 @@ func Test_Pids_Fail(t *testing.T) {
 		t.Errorf("wrong getted pid nums: %v/%d", ret, len(ret))
 	}
 }
-
 func Test_Pid_exists(t *testing.T) {
 	checkPid := os.Getpid()
 
@@ -276,3 +274,18 @@ func Test_Process_CreateTime(t *testing.T) {
 		t.Errorf("process created time is wrong.")
 	}
 }
+
+func Test_Parent(t *testing.T) {
+	p := testGetProcess()
+
+	c, err := p.Parent()
+	if err != nil {
+		t.Errorf("error %v", err)
+	}
+	if c == nil {
+		t.Errorf("could not get parent")
+	}
+	if c.Pid == 0 {
+		t.Errorf("wrong parent pid")
+	}
+}